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(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	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: 
def main():
    Q = int(input())
    XY = []
    for i in range(Q):
        X = input()
        Y = input()
        XY.append((X,Y))
    for X,Y in XY:
        
        LX,LY = len(X), len(Y)
        dp = [0 for _ in range(LY+1)]

        for i in range(LX):
            ex = dp[:]
            for j in range(LY):
                if X[i] == Y[j]:
                    dp[j+1] = ex[j] + 1
                elif dp[j+1] < dp[j]:
                    dp[j+1] = dp[j]
        print(dp[-1])


if __name__ == "__main__":
    main()

Python: n=int(input())

for i in range(n):
    a=list(input())
    b=list(input())
    x=len(a)+1
    y=len(b)+1

    r=[[0 for j in range(y)]for i in range(x)]

    for j in range(1,x):
        for k in range(1,y):
            c=max(r[j-1][k-1],r[j-1][k],r[j][k-1])
            if a[j-1]==b[k-1]:
                c=max(r[j-1][k-1]+1,r[j-1][k],r[j][k-1])
            
            r[j][k]=c    
    print(r[x-1][y-1])

Python: def Ics(x, y):
    a = len(x)
    b = len(y)
    c1 = [0] * (b + 1)

    for i in range(a):
        d = x[i]
        c2 = c1[:]
        for j in range(n):
            if d == y[j]:
                c1[j + 1] = c2[j] + 1
            elif c1[j + 1] < c1[j]:
                c1[j + 1] = c1[j]
    return (c1[-1])

q = int(input().rstrip())
r = []
for k in range(q):
    s1 = input().rstrip()
    s2 = input().rstrip()
    r.append(Ics(s1, s2))

print(*r, sep = "\n")

Python: def calc_lcs(X, Y):
    from array import array
    max_lcs = 0
    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]
            max_lcs = max(max_lcs, c[i*1001 + j])
    return max_lcs


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: from collections import defaultdict
from bisect import bisect_left, bisect, insort_left, insort
INF = 10000
def lcs(s1, s2):
    c = defaultdict(list)
    for i, s in enumerate(s1):
        c[s].append(i)
    for s in set(s2):
        c[s].append(INF)
    def g(li, a):
        for i in li:
            if i >= a:
                return i
        return -1
    dp = []
    for s2_k in s2:
        bgn_idx = 0
        for i, cur_idx in enumerate(dp):
            chr_idx = c[s2_k][bisect_left(c[s2_k], bgn_idx)]
            if chr_idx == INF:
                break
            dp[i] = min(cur_idx, chr_idx + 1)
            bgn_idx = cur_idx
        else:
            chr_idx = c[s2_k][bisect_left(c[s2_k], bgn_idx)]
            if chr_idx != INF:
                dp.append(chr_idx + 1)
    return len(dp)
def solve():
    N = int(input())
    for _ in range(N):
        x = input()
        y = input()
        print(lcs(x, y))
solve()

Python: def lcs(X,Y):
    res = [0 for i in range(len(X)+1)]
    for y in Y:
        previous = res[:]
        for i,x in enumerate(X):
            if x == y:
                res[i+1] = previous[i] + 1
            elif res[i] > previous[i+1]:
                res[i+1] = res[i]
    return res[-1]

n = int(input())
for i in range(n):
    X = input()
    Y = input()
    print(lcs(X,Y))

Python: #dj 16D8101012J ito jun
n = int(input())
for _ in range(n):
    a = input()
    b = input()
    na=len(a)
    nb=len(b)
    array = [[0 for i in range(nb+1)] for j in range(na+1)]
    for i in range(1,na+1):
        for j in range(1,nb+1):
            c = 0
            if a[i-1] == b[j-1]:
                c = 1
            array[i][j] = max(
                array[i-1][j],
                array[i][j-1],
                array[i-1][j-1]+c)
    print(array[na][nb])

Python: # -*- coding: utf-8 -*-
def lcs(x, y):
    n = len(x)
    m = len(y)
    dp = [0 for j in range(m + 1)]

    for i in range(1, n + 1):
        dp_prev = dp[:]
        for j in range(1, m + 1):
            if x[i - 1] == y[j - 1]:
                dp[j] = dp_prev[j - 1] + 1
            elif dp_prev[j] < dp[j - 1]:
                dp[j] = dp[j - 1]
            else:
                dp[j] = dp_prev[j]

    return dp[m]


if __name__ == '__main__':
    import sys
    q = int(sys.stdin.readline().strip())
    for i in range(q):
        x = sys.stdin.readline().strip()
        y = sys.stdin.readline().strip()
        print(lcs(x, y))

Python: 
def resolve():
    def lcs(s1, s2):
        """
        文字列S, Tのlongest common subsequenceの長さを返す
        なお、longest common substringではない
        （要素同士がとなりあっていなくてもいい）ことに注意！
        """

        dp = []
        for s2_k in s2:
            bgn_idx = 0
            for i, cur_idx in enumerate(dp):
                # bgn_idx以降でs2_kを探す
                chr_idx = s1.find(s2_k, bgn_idx) + 1
                if not chr_idx:
                    break
                dp[i] = min(cur_idx, chr_idx)
                bgn_idx = cur_idx
            else:
                chr_idx = s1.find(s2_k, bgn_idx) + 1
                if chr_idx:
                    dp.append(chr_idx)
        return len(dp)

    q = int(input())
    for i in range(q):
        S = str(input())
        T = str(input())
        print(lcs(S, T))


resolve()