commit 9fcf8e29214210612d545bed50d7f889800ac639
Author: Alexander Kiryukhin <a.kiryukhin@mail.ru>
Date:   Sun May 1 21:50:12 2022 +0300

    Initial

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..2fb2e74
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,675 @@
+### GNU GENERAL PUBLIC LICENSE
+
+Version 3, 29 June 2007
+
+Copyright (C) 2007 Free Software Foundation, Inc.
+<https://fsf.org/>
+
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+
+### Preamble
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+
+#### 12. No Surrender of Others' Freedom.
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+#### 13. Use with the GNU Affero General Public License.
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+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
+ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT
+NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR
+LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM
+TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER
+PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+#### 17. Interpretation of Sections 15 and 16.
+
+If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+END OF TERMS AND CONDITIONS
+
+### How to Apply These Terms to Your New Programs
+
+If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these
+terms.
+
+To do so, attach the following notices to the program. It is safest to
+attach them to the start of each source file to most effectively state
+the exclusion of warranty; and each file should have at least the
+"copyright" line and a pointer to where the full notice is found.
+
+        <one line to give the program's name and a brief idea of what it does.>
+        Copyright (C) <year>  <name of author>
+
+        This program is free software: you can redistribute it and/or modify
+        it under the terms of the GNU General Public License as published by
+        the Free Software Foundation, either version 3 of the License, or
+        (at your option) any later version.
+
+        This program is distributed in the hope that it will be useful,
+        but WITHOUT ANY WARRANTY; without even the implied warranty of
+        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+        GNU General Public License for more details.
+
+        You should have received a copy of the GNU General Public License
+        along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper
+mail.
+
+If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+        <program>  Copyright (C) <year>  <name of author>
+        This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+        This is free software, and you are welcome to redistribute it
+        under certain conditions; type `show c' for details.
+
+The hypothetical commands \`show w' and \`show c' should show the
+appropriate parts of the General Public License. Of course, your
+program's commands might be different; for a GUI interface, you would
+use an "about box".
+
+You should also get your employer (if you work as a programmer) or
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary. For more information on this, and how to apply and follow
+the GNU GPL, see <https://www.gnu.org/licenses/>.
+
+The GNU General Public License does not permit incorporating your
+program into proprietary programs. If your program is a subroutine
+library, you may consider it more useful to permit linking proprietary
+applications with the library. If this is what you want to do, use the
+GNU Lesser General Public License instead of this License. But first,
+please read <https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/channels/doc.go b/channels/doc.go
new file mode 100644
index 0000000..0ac1c76
--- /dev/null
+++ b/channels/doc.go
@@ -0,0 +1,2 @@
+// Функции работы над каналами
+package channels
diff --git a/channels/fanin.go b/channels/fanin.go
new file mode 100644
index 0000000..679aeee
--- /dev/null
+++ b/channels/fanin.go
@@ -0,0 +1,23 @@
+package channels
+
+import "sync/atomic"
+
+// FanIn сливает несколько каналов в один
+func FanIn[T any](chans ...chan T) chan T {
+	out := make(chan T)
+	workers := int64(len(chans))
+	for _, ch := range chans {
+		func(ch chan T) {
+			go func() {
+				for t := range ch {
+					out <- t
+				}
+				atomic.AddInt64(&workers, -1)
+				if workers == 0 {
+					close(out)
+				}
+			}()
+		}(ch)
+	}
+	return out
+}
diff --git a/channels/fanin_test.go b/channels/fanin_test.go
new file mode 100644
index 0000000..dd0c889
--- /dev/null
+++ b/channels/fanin_test.go
@@ -0,0 +1,57 @@
+package channels
+
+import (
+	"reflect"
+	"sort"
+	"testing"
+)
+
+func TestFanIn(t *testing.T) {
+	type args struct {
+		chans [][]int
+	}
+	tests := []struct {
+		name string
+		args args
+		want []int
+	}{
+		{
+			name: "test fanin",
+			args: args{
+				chans: [][]int{
+					{1, 2, 3},
+					{4, 5, 6},
+					{7, 8, 9},
+				},
+			},
+			want: []int{1, 2, 3, 4, 5, 6, 7, 8, 9},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := []int{}
+			chans := make([]chan int, len(tt.args.chans))
+			for i, v := range tt.args.chans {
+				func(i int, v []int) {
+					chans[i] = make(chan int, len(v))
+					go func(i int, v []int) {
+						for _, v2 := range v {
+							chans[i] <- v2
+						}
+						close(chans[i])
+					}(i, v)
+				}(i, v)
+			}
+
+			ch := FanIn(chans...)
+
+			for o := range ch {
+				got = append(got, o)
+			}
+			sort.Ints(got)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("FanIn() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/channels/fanout.go b/channels/fanout.go
new file mode 100644
index 0000000..23a32b4
--- /dev/null
+++ b/channels/fanout.go
@@ -0,0 +1,23 @@
+package channels
+
+// FanOut раскидывает очередь канала на несколько каналов равномерно
+func FanOut[T any](in chan T, workers int) []chan T {
+	out := make([]chan T, workers)
+	for i := 0; i < workers; i++ {
+		out[i] = make(chan T)
+	}
+	go func() {
+		i := 0
+		for t := range in {
+			out[i] <- t
+			i++
+			if i == workers {
+				i = 0
+			}
+		}
+		for i := 0; i < workers; i++ {
+			close(out[i])
+		}
+	}()
+	return out
+}
diff --git a/channels/fanout_test.go b/channels/fanout_test.go
new file mode 100644
index 0000000..f8b0380
--- /dev/null
+++ b/channels/fanout_test.go
@@ -0,0 +1,48 @@
+package channels
+
+import (
+	"reflect"
+	"sort"
+	"testing"
+)
+
+func TestFanOut(t *testing.T) {
+	type args struct {
+		in      []int
+		workers int
+	}
+	tests := []struct {
+		name string
+		args args
+	}{
+		{
+			name: "test fanout - fanin",
+			args: args{
+				in:      []int{1, 2, 3, 4, 5, 6, 7, 8, 9},
+				workers: 2,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			in := make(chan int)
+			go func() {
+				for _, v := range tt.args.in {
+					in <- v
+				}
+				close(in)
+			}()
+
+			ch := FanOut(in, tt.args.workers)
+			gotCh := FanIn(ch...)
+			got := []int{}
+			for v := range gotCh {
+				got = append(got, v)
+			}
+			sort.Ints(got)
+			if !reflect.DeepEqual(got, tt.args.in) {
+				t.Errorf("FanIn() = %v, want %v", got, tt.args.in)
+			}
+		})
+	}
+}
diff --git a/collections/doc.go b/collections/doc.go
new file mode 100644
index 0000000..ebb2322
--- /dev/null
+++ b/collections/doc.go
@@ -0,0 +1,2 @@
+// Функции работы над обобщенными коллекциями
+package collections
diff --git a/collections/merge.go b/collections/merge.go
new file mode 100644
index 0000000..6fcf875
--- /dev/null
+++ b/collections/merge.go
@@ -0,0 +1,41 @@
+package collections
+
+import "go.neonxp.dev/extra/utils"
+
+// MergeScalar стабильное слияние двух слайсов скаляров
+func MergeScalar[T utils.Scalar](s1, s2 []T) []T {
+	i, j := 0, 0
+	len1, len2 := len(s1), len(s2)
+	result := make([]T, 0, len1+len2)
+	for i < len1 && j < len2 {
+		if s1[i] < s2[j] {
+			result = append(result, s1[i])
+			i++
+			continue
+		}
+		result = append(result, s2[j])
+		j++
+	}
+	result = append(result, s1[i:]...)
+	result = append(result, s2[j:]...)
+	return result
+}
+
+// Merge стабильное слияние двух слайсов
+func Merge[T utils.Sortable[T]](s1, s2 []T) []T {
+	i, j := 0, 0
+	len1, len2 := len(s1), len(s2)
+	result := make([]T, 0, len1+len2)
+	for i < len1 && j < len2 {
+		if s1[i].Less(s2[j]) {
+			result = append(result, s1[i])
+			i++
+			continue
+		}
+		result = append(result, s2[j])
+		j++
+	}
+	result = append(result, s1[i:]...)
+	result = append(result, s2[j:]...)
+	return result
+}
diff --git a/collections/merge_test.go b/collections/merge_test.go
new file mode 100644
index 0000000..27f5ba0
--- /dev/null
+++ b/collections/merge_test.go
@@ -0,0 +1,92 @@
+package collections
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestMergeScalar(t *testing.T) {
+	type args struct {
+		s1 []int
+		s2 []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want []int
+	}{
+		{
+			name: "test 1",
+			args: args{
+				s1: []int{1, 2, 4, 5, 6},
+				s2: []int{3, 3},
+			},
+			want: []int{1, 2, 3, 3, 4, 5, 6},
+		},
+		{
+			name: "test 2",
+			args: args{
+				s1: []int{1, 3, 5, 7},
+				s2: []int{0, 2, 4, 6, 8},
+			},
+			want: []int{0, 1, 2, 3, 4, 5, 6, 7, 8},
+		},
+		{
+			name: "test 3",
+			args: args{
+				s1: []int{8, 6, 4, 2, 0},
+				s2: []int{1, 3, 5, 7},
+			},
+			want: []int{1, 3, 5, 7, 8, 6, 4, 2, 0},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := MergeScalar(tt.args.s1, tt.args.s2); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("MergeScalar() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestMerge(t *testing.T) {
+	type args struct {
+		s1 []*myType
+		s2 []*myType
+	}
+	tests := []struct {
+		name string
+		args args
+		want []*myType
+	}{
+		{
+			name: "test1",
+			args: args{
+				s1: []*myType{
+					{400}, {200}, {100},
+				},
+				s2: []*myType{
+					{300},
+				},
+			},
+			want: []*myType{
+				{400}, {300}, {200}, {100},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Merge(tt.args.s1, tt.args.s2); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Merge() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+type myType struct {
+	Weight int
+}
+
+func (t *myType) Less(t2 *myType) bool {
+	return t2.Weight < t.Weight
+}
diff --git a/doc.md b/doc.md
new file mode 100755
index 0000000..fae5397
--- /dev/null
+++ b/doc.md
@@ -0,0 +1,278 @@
+<!-- Code generated by gomarkdoc. DO NOT EDIT -->
+
+# channels
+
+```go
+import "go.neonxp.dev/extra/channels"
+```
+
+Функции работы над каналами
+
+## Index
+
+- [func FanIn[T any](chans ...chan T) chan T](<#func-fanin>)
+- [func FanOut[T any](in chan T, workers int) []chan T](<#func-fanout>)
+
+
+## func FanIn
+
+```go
+func FanIn[T any](chans ...chan T) chan T
+```
+
+FanIn сливает несколько каналов в один
+
+## func FanOut
+
+```go
+func FanOut[T any](in chan T, workers int) []chan T
+```
+
+FanOut раскидывает очередь канала на несколько каналов равномерно
+
+# collections
+
+```go
+import "go.neonxp.dev/extra/collections"
+```
+
+Функции работы над обобщенными коллекциями
+
+## Index
+
+- [func Merge[T utils.Sortable[T]](s1, s2 []T) []T](<#func-merge>)
+- [func MergeScalar[T utils.Scalar](s1, s2 []T) []T](<#func-mergescalar>)
+
+
+## func Merge
+
+```go
+func Merge[T utils.Sortable[T]](s1, s2 []T) []T
+```
+
+Merge стабильное слияние двух слайсов
+
+## func MergeScalar
+
+```go
+func MergeScalar[T utils.Scalar](s1, s2 []T) []T
+```
+
+MergeScalar стабильное слияние двух слайсов скаляров
+
+# levenshtein
+
+```go
+import "go.neonxp.dev/extra/levenshtein"
+```
+
+Пакет с функциями получения редакторских правок по Левенштейну
+
+## Index
+
+- [type Edit](<#type-edit>)
+  - [func Levenshtein[T comparable](s1, s2 []T, cost EditCost[T]) []Edit](<#func-levenshtein>)
+  - [func String(s1, s2 string) []Edit](<#func-string>)
+  - [func Strings(s1, s2 []string) []Edit](<#func-strings>)
+- [type EditCost](<#type-editcost>)
+- [type EditType](<#type-edittype>)
+
+
+## type Edit
+
+Edit редакторская правка описывающее одно действие над исходной последовательностью
+
+```go
+type Edit struct {
+    Type EditType // Тип правки: Вставка/Замена/Удаление
+    Idx1 int      // Индекс элемента из первой последовательности
+    Idx2 int      // Индекс элемента из второй последовательности
+}
+```
+
+### func Levenshtein
+
+```go
+func Levenshtein[T comparable](s1, s2 []T, cost EditCost[T]) []Edit
+```
+
+Levenshtein возвращает последовательность правок для превращения последовательности элементов s1 в s2 с учетом стоимостей операций возвращаемых функцией cost TODO в алгоритме не предусмотрена экономия памяти ¯\\\_\(ツ\)\_/¯
+
+### func String
+
+```go
+func String(s1, s2 string) []Edit
+```
+
+String возвращает последовательность правок для превращения строки s1 в строку s2
+
+### func Strings
+
+```go
+func Strings(s1, s2 []string) []Edit
+```
+
+Strings возвращает последовательность правок для превращения слайса строк s1 в слайс строк s2
+
+## type EditCost
+
+EditCost функция возвращающая стоимость действия t над элементами from\, to
+
+```go
+type EditCost[T comparable] func(t EditType, from *T, to *T) int
+```
+
+## type EditType
+
+EditType тип правки
+
+```go
+type EditType int
+```
+
+```go
+const (
+    Insert  EditType = iota // Вставка
+    Replace                 // Замена
+    Delete                  // Удаление
+)
+```
+
+# math
+
+```go
+import "go.neonxp.dev/extra/math"
+```
+
+Пакет с математическими функциями над обобщенными типами
+
+## Index
+
+- [func Max[T utils.Sortable[T]](a ...T) T](<#func-max>)
+- [func MaxScalar[T utils.Scalar](a ...T) T](<#func-maxscalar>)
+- [func Min[T utils.Sortable[T]](a ...T) T](<#func-min>)
+- [func MinScalar[T utils.Scalar](a ...T) T](<#func-minscalar>)
+
+
+## func Max
+
+```go
+func Max[T utils.Sortable[T]](a ...T) T
+```
+
+Max возвращает максимальное из переданных Sortable значений
+
+## func MaxScalar
+
+```go
+func MaxScalar[T utils.Scalar](a ...T) T
+```
+
+MaxScalar возвращает максимальное из переданных скалярных значений
+
+## func Min
+
+```go
+func Min[T utils.Sortable[T]](a ...T) T
+```
+
+Min возвращает минимальное из переданных Sortable значений
+
+## func MinScalar
+
+```go
+func MinScalar[T utils.Scalar](a ...T) T
+```
+
+MinScalar возвращает минимальное из переданных скалярных значений
+
+# subseq
+
+```go
+import "go.neonxp.dev/extra/subseq"
+```
+
+Пакет с функциями получения подпоследовательностей \(например\, подстроки\)
+
+## Index
+
+- [func MaxSubsequence(s1, s2 string) string](<#func-maxsubsequence>)
+- [func MaxSubset[T comparable](s1, s2 []T) []T](<#func-maxsubset>)
+- [func MaxSubsetSequence[T comparable](s1, s2 []T) []T](<#func-maxsubsetsequence>)
+- [func MaxSubstring(s1, s2 string) string](<#func-maxsubstring>)
+
+
+## func MaxSubsequence
+
+```go
+func MaxSubsequence(s1, s2 string) string
+```
+
+MaxSubsequence возвращает максимальную общую подпоследовательность символов
+
+## func MaxSubset
+
+```go
+func MaxSubset[T comparable](s1, s2 []T) []T
+```
+
+## func MaxSubsetSequence
+
+```go
+func MaxSubsetSequence[T comparable](s1, s2 []T) []T
+```
+
+## func MaxSubstring
+
+```go
+func MaxSubstring(s1, s2 string) string
+```
+
+MaxSubstring возвращаает максимальную общую подстроку
+
+# utils
+
+```go
+import "go.neonxp.dev/extra/utils"
+```
+
+Всякое разное
+
+## Index
+
+- [func Ptr[T any](t T) *T](<#func-ptr>)
+- [type Scalar](<#type-scalar>)
+- [type Sortable](<#type-sortable>)
+
+
+## func Ptr
+
+```go
+func Ptr[T any](t T) *T
+```
+
+Ptr получение указателя от произвольного значения\, например\, ToPtr\(true\) \-\> \*bool\(true\)
+
+## type Scalar
+
+Scalar соответствует скалярам над которыми определены операции сравнения
+
+```go
+type Scalar interface {
+    // contains filtered or unexported methods
+}
+```
+
+## type Sortable
+
+Sortable соответствует типам над которыми определена операция Less
+
+```go
+type Sortable[T any] interface {
+    Less(T) bool
+}
+```
+
+
+
+Generated by [gomarkdoc](<https://github.com/princjef/gomarkdoc>)
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..748d10c
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module go.neonxp.dev/extra
+
+go 1.18
diff --git a/levenshtein/doc.go b/levenshtein/doc.go
new file mode 100644
index 0000000..a9d3130
--- /dev/null
+++ b/levenshtein/doc.go
@@ -0,0 +1,2 @@
+// Пакет с функциями получения редакторских правок по Левенштейну
+package levenshtein
diff --git a/levenshtein/generic.go b/levenshtein/generic.go
new file mode 100644
index 0000000..4aa3ecf
--- /dev/null
+++ b/levenshtein/generic.go
@@ -0,0 +1,99 @@
+package levenshtein
+
+import (
+	"go.neonxp.dev/extra/math"
+)
+
+// Levenshtein возвращает последовательность правок для превращения последовательности элементов s1 в s2
+// с учетом стоимостей операций возвращаемых функцией cost
+// TODO в алгоритме не предусмотрена экономия памяти ¯\_(ツ)_/¯
+func Levenshtein[T comparable](s1, s2 []T, cost EditCost[T]) []Edit {
+	len1 := len(s1)
+	len2 := len(s2)
+	if cost == nil {
+		cost = EditCost[T](func(t EditType, s1 *T, s2 *T) int {
+			return 1
+		})
+	}
+
+	dp := make([][]int, len1+1)
+	for i := range dp {
+		dp[i] = make([]int, len2+1)
+	}
+	dp[0][0] = 0
+	for i := 0; i < len1; i++ {
+		for j := 0; j < len2; j++ {
+			if i == 0 && j == 0 {
+				continue
+			}
+			switch {
+			case i == 0:
+				dp[0][j] = dp[0][j-1] + cost(Insert, nil, &s2[j])
+			case j == 0:
+				dp[i][0] = dp[i-1][0] + cost(Delete, &s1[i], nil)
+			default:
+				m1 := dp[i-1][j] + cost(Delete, &s1[i], nil)
+				m2 := dp[i][j-1] + cost(Insert, nil, &s2[j])
+				m3 := dp[i-1][j-1] + cost(Replace, &s1[i], &s2[j])
+				dp[i][j] = math.MinScalar(m1, m2, m3)
+			}
+		}
+	}
+	i, j := len1-1, len2-1
+	edits := []Edit{}
+	for i > 0 && j > 0 {
+		m1 := dp[i-1][j] + cost(Delete, &s1[i], nil)
+		m2 := dp[i][j-1] + cost(Insert, nil, &s2[j])
+		m3 := dp[i-1][j-1] + cost(Replace, &s1[i], &s2[j])
+		min := math.MinScalar(m1, m2, m3)
+		if min == m1 {
+			// добавляем удаление символа S1[i]
+			edits = append(edits, Edit{
+				Type: Delete,
+				Idx1: i,
+			})
+			i--
+		}
+		if min == m2 {
+			// добавляем вставку символа S2[j] после S1[i]
+			edits = append(edits, Edit{
+				Type: Insert,
+				Idx1: i,
+				Idx2: j,
+			})
+			j--
+		}
+		if min == m3 {
+			// добавляем замену S1[i] на S2[j]
+			i--
+			j--
+			if s1[i] != s2[j] {
+				edits = append(edits, Edit{
+					Type: Replace,
+					Idx1: i,
+					Idx2: j,
+				})
+			}
+		}
+	}
+	return edits
+}
+
+// EditCost функция возвращающая стоимость действия t над элементами from, to
+type EditCost[T comparable] func(t EditType, from *T, to *T) int
+
+// Edit редакторская правка описывающее одно действие над исходной последовательностью
+type Edit struct {
+	Type EditType // Тип правки: Вставка/Замена/Удаление
+	Idx1 int      // Индекс элемента из первой последовательности
+	Idx2 int      // Индекс элемента из второй последовательности
+}
+
+// EditType тип правки
+type EditType int
+
+const (
+	Insert  EditType = iota // Вставка
+	Replace                 // Замена
+	Delete                  // Удаление
+)
diff --git a/levenshtein/generic_test.go b/levenshtein/generic_test.go
new file mode 100644
index 0000000..11c9611
--- /dev/null
+++ b/levenshtein/generic_test.go
@@ -0,0 +1,115 @@
+package levenshtein
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestLevenshtein2(t *testing.T) {
+	type args struct {
+		s1   []myType
+		s2   []myType
+		cost EditCost[myType]
+	}
+	tests := []struct {
+		name string
+		args args
+		want []Edit
+	}{
+		{
+			name: "test1",
+			args: args{
+				s1: []myType{
+					{
+						a: "a",
+					}, {
+						a: "b",
+					}, {
+						a: "c",
+					},
+				},
+				s2: []myType{
+					{
+						a: "a",
+					}, {
+						a: "d",
+					}, {
+						a: "c",
+					},
+				},
+				cost: EditCost[myType](func(t EditType, from, to *myType) int {
+					return 1
+				}),
+			},
+			want: []Edit{
+				{
+					Type: Replace,
+					Idx1: 1,
+					Idx2: 1,
+				},
+			},
+		},
+		{
+			name: "test2 - costly replace",
+			args: args{
+				s1: []myType{
+					{
+						a: "a",
+					}, {
+						a: "b",
+					}, {
+						a: "c",
+					},
+				},
+				s2: []myType{
+					{
+						a: "a",
+					}, {
+						a: "d",
+					}, {
+						a: "c",
+					},
+				},
+				cost: EditCost[myType](func(t EditType, from, to *myType) int {
+					if t == Replace {
+						return 100
+					}
+					return 1
+				}),
+			},
+			want: []Edit{
+				{
+					Type: Delete,
+					Idx1: 2,
+					Idx2: 0,
+				},
+				{
+					Type: Insert,
+					Idx1: 1,
+					Idx2: 2,
+				},
+				{
+					Type: Delete,
+					Idx1: 1,
+					Idx2: 0,
+				},
+				{
+					Type: Insert,
+					Idx1: 0,
+					Idx2: 1,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Levenshtein(tt.args.s1, tt.args.s2, tt.args.cost); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Levenshtein() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+type myType struct {
+	a string
+}
diff --git a/levenshtein/strings.go b/levenshtein/strings.go
new file mode 100644
index 0000000..a6257d1
--- /dev/null
+++ b/levenshtein/strings.go
@@ -0,0 +1,11 @@
+package levenshtein
+
+// String возвращает последовательность правок для превращения строки s1 в строку s2
+func String(s1, s2 string) []Edit {
+	return Levenshtein([]rune(s1), []rune(s2), nil)
+}
+
+// Strings возвращает последовательность правок для превращения слайса строк s1 в слайс строк s2
+func Strings(s1, s2 []string) []Edit {
+	return Levenshtein(s1, s2, nil)
+}
diff --git a/levenshtein/strings_test.go b/levenshtein/strings_test.go
new file mode 100644
index 0000000..fe103e4
--- /dev/null
+++ b/levenshtein/strings_test.go
@@ -0,0 +1,64 @@
+package levenshtein
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestString(t *testing.T) {
+	type args struct {
+		s1 string
+		s2 string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []Edit
+	}{
+		{
+			name: "test1",
+			args: args{
+				s1: "абвзгде",
+				s2: "абвжгде",
+			},
+			want: []Edit{
+				{
+					Type: Replace,
+					Idx1: 3,
+					Idx2: 3,
+				},
+			},
+		},
+		{
+			name: "test2",
+			args: args{
+				s1: "абавзгд",
+				s2: "абввжгде",
+			},
+			want: []Edit{
+				{
+					Type: Insert, // абавзгд -> абавзгд[е]
+					Idx1: 6,
+					Idx2: 7,
+				},
+				{
+					Type: Replace, // абав[з]где -> абав[ж]где
+					Idx1: 4,
+					Idx2: 4,
+				},
+				{
+					Type: Replace, // аб[а]вжгде -> аб[в]вжгде
+					Idx1: 2,
+					Idx2: 2,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := String(tt.args.s1, tt.args.s2); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("LevenshteinString() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/math/doc.go b/math/doc.go
new file mode 100644
index 0000000..1d3cbf5
--- /dev/null
+++ b/math/doc.go
@@ -0,0 +1,2 @@
+// Пакет с математическими функциями над обобщенными типами
+package math
diff --git a/math/mimax.go b/math/mimax.go
new file mode 100644
index 0000000..546afba
--- /dev/null
+++ b/math/mimax.go
@@ -0,0 +1,63 @@
+package math
+
+import "go.neonxp.dev/extra/utils"
+
+// MinScalar возвращает минимальное из переданных скалярных значений
+func MinScalar[T utils.Scalar](a ...T) T {
+	i := -1
+	for j, v := range a {
+		if i == -1 {
+			i = j
+			continue
+		}
+		if v < a[i] {
+			i = j
+		}
+	}
+	return a[i]
+}
+
+// MaxScalar возвращает максимальное из переданных скалярных значений
+func MaxScalar[T utils.Scalar](a ...T) T {
+	i := -1
+	for j, v := range a {
+		if i == -1 {
+			i = j
+			continue
+		}
+		if v > a[i] {
+			i = j
+		}
+	}
+	return a[i]
+}
+
+// Min возвращает минимальное из переданных Sortable значений
+func Min[T utils.Sortable[T]](a ...T) T {
+	i := -1
+	for j, v := range a {
+		if i == -1 {
+			i = j
+			continue
+		}
+		if v.Less(a[i]) {
+			i = j
+		}
+	}
+	return a[i]
+}
+
+// Max возвращает максимальное из переданных Sortable значений
+func Max[T utils.Sortable[T]](a ...T) T {
+	i := -1
+	for j, v := range a {
+		if i == -1 {
+			i = j
+			continue
+		}
+		if a[i].Less(v) {
+			i = j
+		}
+	}
+	return a[i]
+}
diff --git a/math/minmax_test.go b/math/minmax_test.go
new file mode 100644
index 0000000..00211e2
--- /dev/null
+++ b/math/minmax_test.go
@@ -0,0 +1,58 @@
+package math
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestMin(t *testing.T) {
+	type args struct {
+		a []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "test1",
+			args: args{
+				a: []int{8, 3, 6},
+			},
+			want: 3,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := MinScalar(tt.args.a...); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Min() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestMax(t *testing.T) {
+	type args struct {
+		a []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "test1",
+			args: args{
+				a: []int{8, 13, 6},
+			},
+			want: 13,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := MaxScalar(tt.args.a...); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Max() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/readme.md b/readme.md
new file mode 100755
index 0000000..ca65aeb
--- /dev/null
+++ b/readme.md
@@ -0,0 +1,11 @@
+# Extra
+
+Пакет с разными полезными функциями без дополнительных зависимостей.
+
+Большинство функций написаны с использованием обобщенных типов. Другие - вызовы этих же функций с конкретными типами для упрощения использования.
+
+[Документация](/doc.md)
+
+Лицензия [GPL-3](https://antirao.ru/gpltrans/gplru.pdf)
+
+Автор: Александр Кирюхин <i@neonxp.dev>
diff --git a/subseq/doc.go b/subseq/doc.go
new file mode 100644
index 0000000..4e4282c
--- /dev/null
+++ b/subseq/doc.go
@@ -0,0 +1,2 @@
+// Пакет с функциями получения подпоследовательностей (например, подстроки)
+package subseq
diff --git a/subseq/generic.go b/subseq/generic.go
new file mode 100644
index 0000000..4415ffb
--- /dev/null
+++ b/subseq/generic.go
@@ -0,0 +1,80 @@
+package subseq
+
+func MaxSubset[T comparable](s1, s2 []T) []T {
+	len1 := len(s1)
+	len2 := len(s2)
+
+	dp := make([][]int, len1+1)
+	for i := range dp {
+		dp[i] = make([]int, len2+1)
+	}
+	max := 0
+	u := 0
+	for i := 0; i < len1; i++ {
+		for j := 0; j < len2; j++ {
+			switch {
+			case i == 0:
+				dp[0][j] = 0
+			case j == 0:
+				dp[i][0] = 0
+			case s1[i] != s2[j]:
+				dp[i][j] = 0
+			default:
+				dp[i][j] = dp[i-1][j-1] + 1
+				if dp[i][j] > max {
+					max = dp[i][j]
+					u = i
+				}
+			}
+		}
+	}
+	ret := []T{}
+	for i := max; i > 0; i-- {
+		ret = append(ret, s1[u-i+1])
+	}
+	return ret
+}
+
+func MaxSubsetSequence[T comparable](s1, s2 []T) []T {
+	len1 := len(s1)
+	len2 := len(s2)
+
+	dp := make([][]int, len1+1)
+	for i := range dp {
+		dp[i] = make([]int, len2+1)
+	}
+
+	for i := len1; i >= 0; i-- {
+		for j := len2; j >= 0; j-- {
+			switch {
+			case i == len1, j == len2:
+				dp[i][j] = 0
+			case s1[i] == s2[j]:
+				dp[i][j] = 1 + dp[i+1][j+1]
+			default:
+				max := dp[i+1][j]
+				if dp[i][j+1] > max {
+					max = dp[i][j+1]
+				}
+				dp[i][j] = max
+			}
+		}
+	}
+
+	ret := []T{}
+	i, j := 0, 0
+	for i < len1 && j < len2 {
+		switch {
+		case s1[i] == s2[j]:
+			ret = append(ret, s1[i])
+			i++
+			j++
+		case dp[i+1][j] >= dp[i][j+1]:
+			i++
+		default:
+			j++
+		}
+	}
+
+	return ret
+}
diff --git a/subseq/strings.go b/subseq/strings.go
new file mode 100644
index 0000000..6be73e9
--- /dev/null
+++ b/subseq/strings.go
@@ -0,0 +1,11 @@
+package subseq
+
+// MaxSubstring возвращаает максимальную общую подстроку
+func MaxSubstring(s1, s2 string) string {
+	return string(MaxSubset([]rune(s1), []rune(s2)))
+}
+
+// MaxSubsequence возвращает максимальную общую подпоследовательность символов
+func MaxSubsequence(s1, s2 string) string {
+	return string(MaxSubsetSequence([]rune(s1), []rune(s2)))
+}
diff --git a/subseq/strings_test.go b/subseq/strings_test.go
new file mode 100644
index 0000000..b35b139
--- /dev/null
+++ b/subseq/strings_test.go
@@ -0,0 +1,77 @@
+package subseq
+
+import (
+	"testing"
+)
+
+func TestMaxSubstring(t *testing.T) {
+	type args struct {
+		s1 string
+		s2 string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "test",
+			args: args{
+				s1: "какая то строка текста",
+				s2: "другая строка другого",
+			},
+			want: " строка ",
+		},
+		{
+			name: "test2",
+			args: args{
+				s1: "qwertyuiop",
+				s2: "asdfghertyjklzxcvzxqertyuvzvb",
+			},
+			want: "ertyu",
+		},
+		{
+			name: "empty",
+			args: args{
+				s1: "abc",
+				s2: "def",
+			},
+			want: "",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := MaxSubstring(tt.args.s1, tt.args.s2); got != tt.want {
+				t.Errorf("MaxSubstring() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestMaxSubseq(t *testing.T) {
+	type args struct {
+		s1 string
+		s2 string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "test",
+			args: args{
+				s1: "nematode knowledge",
+				s2: "empty bottle",
+			},
+			want: "emt ole",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := MaxSubsequence(tt.args.s1, tt.args.s2); got != tt.want {
+				t.Errorf("MaxSubseq() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/utils/constraints.go b/utils/constraints.go
new file mode 100644
index 0000000..c63ea63
--- /dev/null
+++ b/utils/constraints.go
@@ -0,0 +1,11 @@
+package utils
+
+// Scalar соответствует скалярам над которыми определены операции сравнения
+type Scalar interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr | ~float32 | ~float64 | ~string
+}
+
+// Sortable соответствует типам над которыми определена операция Less
+type Sortable[T any] interface {
+	Less(T) bool
+}
diff --git a/utils/doc.go b/utils/doc.go
new file mode 100644
index 0000000..9087888
--- /dev/null
+++ b/utils/doc.go
@@ -0,0 +1,2 @@
+// Всякое разное
+package utils
diff --git a/utils/ptr.go b/utils/ptr.go
new file mode 100644
index 0000000..449f499
--- /dev/null
+++ b/utils/ptr.go
@@ -0,0 +1,6 @@
+package utils
+
+// Ptr получение указателя от произвольного значения, например, ToPtr(true) -> *bool(true)
+func Ptr[T any](t T) *T {
+	return &t
+}