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] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// 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: import sys
sys.setrecursionlimit(200000)
from functools import lru_cache
from collections import defaultdict
from bisect import bisect_left, bisect, insort_left, insort
q = int(input())
for _ in range(q):
    x = input()
    y = input()
    len_x = len(x)
    len_y = len(y)
    if len_x < len_y:
        len_x, len_y = len_y, len_x
        x, y = y, x
    c = defaultdict(list)
    for i, s in enumerate(x):
        c[s].append(i)
    ans = 0
    @lru_cache(maxsize=1000)
    def f(x_i, y_i, cnt):
        if x_i >= len_x or y_i >= len_y:
            global ans
            if ans < cnt:
                ans = cnt
            return
        f(x_i, y_i + 1, cnt)
        s = bisect_left(c[y[y_i]], x_i)
        if s < len(c[y[y_i]]) and c[y[y_i]][s] < len_x:
            f(c[y[y_i]][s] + 1, y_i + 1, cnt + 1)
    f(0, 0, 0)
    print(ans)

Python: def lcs(str1,str2):
    c=[[0 for _ in range(1000)] for _ in range(1000)]
    m=len(str1)
    n=len(str2)
    maxl=0
    str1=" "+str1
    str2=" "+str2

    i=1
    j=1
    while(i<=m):
        while(j<=n):
            if(str1[i]==str2[j]):
                c[i][j]=c[i-1][j-1]+1
              #  print(c[i][j])
            else:
                c[i][j]=max(c[i-1][j],c[i][j-1])
            maxl=max(maxl,c[i][j])
            j+=1
        i+=1
        j=0

    return maxl

def main():
    n=int(input())
    i=0
    while(i<n):
        str1=str(input())
        str2=str(input())
        print(int(lcs(str1,str2)))
        i+=1

main()

Python: e=input
a=[]
for _ in[0]*int(e()):
 X,z=e(),[]
 for y in e():
  s=i=0
  for k in z:
   t=X.find(y,s)+1
   if t<1:break
   if t<k:z[i]=t
   s=k;i+=1
  else:
   t=X.find(y,s)+1
   if t:z+=[t]
 a+=[z]
print('\n'.join(map(str,map(len,a))))

Python: def lcs(s1, s2):

    dp = []

    for s2_k in s2:

        bgn_idx = 0

        for i, cur_idx in enumerate(dp):

            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)



def solve():

    N = int(input())

    for _ in range(N):

        x = input()

        y = input()

        print(lcs(x, y))



if __name__ == '__main__':

    solve()

Python: # 38

import sys


def lcs(X, Y):
    l_x = len(X)
    l_y = len(Y)
    # dp[i][j] : Xのi文字目、Yのj文字目までから構成される最長部分列数
    dp = [[0] * (l_y+1) for _ in range(l_x+1)]
    for i in range(l_x):
        for j in range(l_y):
            if X[i] == Y[j]:
                dp[i+1][j+1] = dp[i][j]+1
            else:
                dp[i+1][j+1] = max(dp[i+1][j], dp[i][j+1])
    return dp[-1][-1]


def lcs_s(X, Y):
    L = []
    for yk in Y:
        bgn_idx = 0
        for i, cur_idx in enumerate(L):
            chr_idx = X.find(yk, bgn_idx) + 1
            if not chr_idx:
                break
            L[i] = min(cur_idx, chr_idx)
            bgn_idx = cur_idx
        else:
            chr_idx = X.find(yk, bgn_idx) + 1
            if chr_idx:
                L.append(chr_idx)
    return len(L)


Q = int(input())
for _ in range(Q):
    X = sys.stdin.readline().rstrip()
    Y = sys.stdin.readline().rstrip()
    print(lcs_s(X, Y))

Python: import sys

def dp_init(m, n):
    return [[0] * n] * m

def solve(str_a, str_b):
    dp = dp_init(len(str_a), len(str_b))
    return rec(len(str_a), len(str_b), str_a, str_b, dp)

def rec(i, j, str_a, str_b, dp):
    if i-1 == 0 or j-1 == 0:
        return 0
    if dp[i-1][j-1] > 0:
        return dp[i-1][j-1]
    if str_a[i-1] == str_b[j-1]:
        dp[i-1][j-1] = rec(i-1, j-1, str_a, str_b, dp) + 1
        print("(%d, %d) : %d" % (i-1, j-1, dp[i-1][j-1]))
        return dp[i-1][j-1]
    dp[i-1][j-1] = max(rec(i, j-1, str_a, str_b, dp), rec(i-1, j, str_a, str_b, dp))
    print("(%d, %d) : %d" % (i-1, j-1, dp[i-1][j-1]))
    return dp[i-1][j-1]

nb_pairs = int(input())
pairs = []
for i in range(0, nb_pairs):
    pairs.append((input(), input()))

for i in range(0, nb_pairs):
    str_a, str_b = pairs[i]
    print(solve(str_a, str_b))