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: #!/usr/bin/env python3
# -*- coding: utf-8 -*-

import sys
import re
import math
import collections
import itertools
import functools

DEBUG = True
DEBUG = False

def dbg(*args):
    if DEBUG:
        print("DBG: ", file=sys.stderr, end="")
        print(*args, file=sys.stderr)

dp = [[0] * 1001 for _ in range(1001)]

def solve(x, y):
    m = len(x)
    n = len(y)

    for i in range(m+1):
        dp[i][0] = 0
    for j in range(n+1):
        dp[0][j] = 0

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

    return dp[m][n]

def main():
    n = int(input())

    for _ in range(n):
        x = input()
        y = input()
        dbg(x, y)

        lcs_len = solve(x, y)
        print(lcs_len)

if __name__ == "__main__": main()

Python: from functools import lru_cache


n = int(input())

# result = []

@lru_cache()
def search(s1, s2, rs=''):

    if not s1:
        # print(rs)
        result.append(rs)
        return

    if s1:
        s1_head, s1_body = s1[0], s1[1:]
        for idx2, s2_tgt in enumerate(s2):
            if s1_head == s2_tgt:
                search(s1_body, s2[idx2+1:], rs+s1_head)

    if s2:
        s2_head, s2_body = s2[0], s2[1:]
        for idx1, s1_tgt in enumerate(s1):
            if s2_head == s1_tgt:
                search(s1[idx1+1:], s2_body, rs+s2_head)

    if s1 and s2:
        search(s1[1:], s2[1:], rs)

    result.append(rs)
    # print(rs)


for _ in range(n):
    result = []
    s1 = input()
    s2 = input()
    search(s1, s2)
    print(max(map(len, result)))

Python: def solve(x,y):
    lx=len(x)
    ly=len(y)
    dp=[0]*(ly+1)
    for i in range(lx):
        bef=dp[:]
        for j in range(ly): 
            #print(str(i)+" "+str(j))
            if x[i]==y[j]:
                dp[j+1]=bef[j]+1
            elif dp[j+1]<dp[j]:
                dp[j+1]=dp[j]
    print(dp[ly])
q=int(input())
for i in range(q):
    x=list(input())
    y=list(input())
    solve(x,y)

Python: def lcs(x, y):
    m = len(x)
    n = len(y)
    c = [0] * (n + 1)
    for i in range(m):
        tmp = x[i]
        c_ = c[:]
        for j in range(n):
            if tmp == y[j]:
                c[j + 1] = c_[j] + 1
            elif c[j + 1] < c[j]:
                c[j + 1] = c[j]
    return c[-1]


q = int(input())
ans = []
for _ in range(q):
    x = input()
    y = input()
    ans.append(lcs(x, y))

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

Python: # -*- coding: utf-8 -*-
"""
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C

????????±?????¨??????
"""
import sys
from sys import stdin
input = stdin.readline


C = []
def calc_lcs4(X, Y):
    global C
    X = ' ' + X
    Y = ' ' + Y
    m = len(X)
    n = len(Y)

    C = [[0]*(n+1) for _ in range(m+1)] #  ???????????§??¨???

    max_lcs = 0

    pre_row = C[0]
    for i in range(1, m):
        row = C[i]
        XX = X[i]
        for j, YY in enumerate(Y):
            if XX == YY:
                pr_j1 = pre_row[j - 1]
                row[j] = pr_j1 + 1
                if pr_j1+1 > max_lcs:
                   max_lcs = pr_j1 + 1
            else:
                pr_j = pre_row[j]
                r_j1 = row[j-1]
                if pr_j >= r_j1:
                    row[j] = pr_j
                else:
                    row[j] = r_j1
        pre_row = row

    print(max_lcs)


if __name__ == '__main__':
    num = int(input())

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

        result = calc_lcs4(X, Y)

Python: #!/usr/bin/env python
from __future__ import division, print_function
from sys import stdin


def main():
    n = int(stdin.readline())

    for _ in range(n):
        x = stdin.readline().rstrip()
        y = stdin.readline().rstrip()

        m = len(x)
        n = len(y)
        #assert 1 <= m <= 1000
        #assert 1 <= n <= 1000

        c = [[0]*(n+1) for _ in range(m+1)]

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

        print(c[-1][-1])


main()

Python: def get_longest_count(X, Y):
  count = 0
  while len(X) > 0 and len(Y) > 0:
    if X[-1] != Y[-1]:
      return count + max(get_longest_count(X[:-1], Y), get_longest_count(X, Y[:-1]))
    else:
      X = X[:-1]
      Y = Y[:-1]
      count += 1
  return count

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

Python: def len_LCS(X,Y):
    x_l = len(X)
    y_l = len(Y)
    lcs_row = [0 for _ in range(x_l+1)]
    for j in range(y_l):
        y_j = Y[j]
        lcs_row_p = lcs_row[:]
        # lcs_row_p: [i] [i+1]
        # lcs_row  : [i] [i+1]
        for i in range(x_l):
            if X[i] == y_j:
                lcs_row[i+1] = lcs_row_p[i] + 1
            elif lcs_row[i] > lcs_row_p[i+1]:
                lcs_row[i+1] = lcs_row[i]
    return lcs_row[-1]
        
if __name__=='__main__':
    n = int(input())
    for _ in range(n):
        X = input()
        Y = input()
        print(len_LCS(X,Y))

Python: DP_MAX = 1000
dp = [0] * (DP_MAX + 1)

for i in range(DP_MAX + 1):
  dp[i] = [0] * (DP_MAX + 1)

def lcs(s, t):
  slen = len(s)
  tlen = len(t)

  for i in range(1, slen + 1):
    dp_i   = dp[i]
    dp_i_1 = dp[i-1]
    for j in range(1, tlen + 1):
      if s[i-1] == t[j-1]:
        dp_i[j] = dp_i_1[j-1] + 1
      else:
        dp_i[j] = max(dp_i[j-1], dp_i_1[j])

  return dp[slen][tlen]

n = int(raw_input())

for i in range(n):
  x = raw_input()
  y = raw_input()
  print(lcs(x, y))