Go: package main

import (
	"fmt"
	"os"
	"strconv"
	"bufio"
	"strings"
	"sort"
)

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				} else {
					dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				}
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

Python: # coding: utf-8

def array2d(d1, d2, init = None):
    return [[init for _ in range(d2)] for _ in range(d1)]


def solve():
    x = input().strip()
    y = input().strip()

    # dp[i][j]: x[:i], y[:j] ???LCS
    # dp[i][j] = max(dp[i-1][j], dp[i][j-1], dp[i-1][j-1]+1(if x[i]==y[j]))
    dp = array2d(len(x), len(y), 0)
    for i in range(len(x)):
        for j in range(len(y)):
            if i == 0 and j == 0:
                dp[0][0] = int(x[0] == y[0])
                continue
            if i > 0:
                dp[i][j] = max(dp[i][j], dp[i-1][j])
            if j > 0:
                dp[i][j] = max(dp[i][j], dp[i][j-1])
            if i > 0 and j > 0:
                cand = dp[i-1][j-1]
            else:
                cand = 0
            dp[i][j] = max(dp[i][j], cand + (x[i] == y[j]))
    return dp[-1][-1]


def main():
    cases = int(input())
    for i in range(cases):
        print(solve())

main()

Python: import bisect
import collections
import heapq
import itertools
import operator
import sys

dp = [[0] * 1010 for _ in range(1010)]

def lcs(x, y):
    for i, c in enumerate(y):
        if c == x[0]:
            dp[0][i] = 1
    for i, c in enumerate(x):
        if c == y[0]:
            dp[i][0] = 1
    for i in range(len(x)):
        for j in range(len(y)):
            if x[i] == y[j]:
                dp[i][j] = dp[i-1][j-1] + 1
            else:
                dp[i][j] = max(dp[i][j-1], dp[i-1][j])
    return dp[len(x)-1][len(y)-1]

def main():
    n = int(sys.stdin.readline())
    for _ in range(n):
        x = sys.stdin.readline().strip()
        y = sys.stdin.readline().strip()
        print(lcs(x, y))


if __name__ == '__main__':
    main()

Python: def calc_lcs(X, Y):
    from array import array
    m = len(X)
    n = len(Y)
    X = ' ' + X
    Y = ' ' + Y
    c = array('I', [0] * (1001 * 1001))
    for i in range(1, m+1):
        for j in range(1, n+1):
            if X[i] == Y[j]:
                c[i*1001 + j] = c[(i-1)*1001 + j - 1] + 1
            elif c[(i-1)*1001 + j] >= c[i*1001 + j - 1]:
                c[i*1001 + j] = c[(i-1)*1001 + j]
            else:
                c[i*1001 + j] = c[i*1001 + j - 1]
    return max(c)


if __name__ == '__main__':
    # ??????????????\???
    num = int(input())
    # f = open('input.txt')
    # num = int(f.readline())

    for _ in range(num):
        X = input()
        Y = input()
        # X = f.readline().strip()
        # Y = f.readline().strip()

        # ???????????????
        result = calc_lcs(X, Y)

        # ???????????¨???
        print(result)

Python: def lcs_len(x, y):
    indices = [0]
    for y_i in y:
        t_index = 0
        for i, index in enumerate(indices, 1):
            c_index = x.find(y_i, t_index) + 1
            if c_index:
                if i < len(indices):
                    t_index = indices[i]
                    indices[i] = min(c_index, t_index)
                else:
                    indices.append(c_index)
                    break
    print(len(indices) - 1)


q = int(input())

for i in range(q):
    ax = input()
    ay = input()
    lcs_len(ax, ay)

Python: m = int(input())
for i in range(m):
    str1 = input()
    str2 = input()
    A = [0 for j in range(len(str2)+1)]
    for char1 in str1:
        A_copy = A[:]
        for j,char2 in enumerate(str2):
            if(char1==char2):
                A[j+1] = A_copy[j]+1
            elif(A[j] > A[j+1]):
                A[j+1] = A[j]
    print(A[-1])

Python: #!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
input:
3
abcbdab
bdcaba
abc
abc
abc
bc

output:
4
3
2

"""
import sys

sys.setrecursionlimit(int(1e5))


def lcs(w1, w2):
    m, n = len(w1), len(w2)
    dp = tuple([0] * (n + 1) for _ in range(m + 1))
    max_l = 0
    for i in range(1, m + 1):
        for j in range(1, n + 1):
            if w1[i - 1] == w2[j - 1]:
                dp[i][j] = dp[i - 1][j - 1] + 1
            else:
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
            max_l = max(max_l, dp[i][j])

    return max_l


def lcs_recursive(w1, w2, m, n):
    if m == 0 or n == 0:
        return 0
    elif w1[m - 1] == w2[n - 1]:
        return 1 + lcs_recursive(w1, w2, m - 1, n - 1)
    else:
        return max(lcs_recursive(w1, w2, m, n - 1), lcs_recursive(w1, w2, m - 1, n))


def solve():
    _input = sys.stdin.readlines()
    pair_num = int(_input[0])
    word_list = _input[1:]
    # assert len(word_list) == 2 * pair_num

    for pair in zip(word_list[::2], word_list[1::2]):
        cw1, cw2 = map(lambda x: x.strip(), pair)
        print(lcs(cw1, cw2))
        # l1, l2 = len(cw1), len(cw2)
        # print(lcs_recursive(cw1, cw2, l1, l2))

    return None


if __name__ == '__main__':
    solve()

Python: q=int(input())
for i in range(q):
    s1=input()
    s2=input()
    ls1=len(s1)
    ls2=len(s2)
    f=[[0 for k in range(ls2+1)] for j in range(ls1+1)]
    f[0][0]=0
    for l in range(ls1+1):
        f[l][0]=0
    for l in range(ls2+1):
        f[0][l]=0
    for j in range(1,ls1+1):
        for k in range(1,ls2+1):
            if s1[j-1]==s2[k-1]:
                f[j][k]=f[j-1][k-1]+1
            else:
                f[j][k]=max(f[j-1][k],f[j][k-1])
    print(f[j][k])

Python: N = int(input())

for _ in range(N):
    x = input()
    y = input()
    m, n = len(x), len(y)
    dp = [0] * (n+1)
    
    for xi in x:
        temp = dp[:]
        for j in range(n):
            if xi == y[j]:
                dp[j+1] = temp[j] + 1
            elif dp[j+1] < dp[j]:
                dp[j+1] = dp[j]
                
    print(dp[-1])