Go: package main

/*
最長共通部分列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func larger(l, r int) int {
	if l > r {
		return l
	}
	return r
}

var memo [1001][1001]int

func countLCS(x, y string) int {
	x = " " + x
	y = " " + y
	max := 0
	for xi := 1; xi < len(x); xi++ {
		for yi := 1; yi < len(y); yi++ {
			if x[xi] == y[yi] {
				memo[xi][yi] = memo[xi-1][yi-1] + 1
			} else {
				memo[xi][yi] = larger(memo[xi-1][yi], memo[xi][yi-1])
			}
			max = larger(max, memo[xi][yi])
		}
	}
	return max
}

func main() {
	scanner := makeScanner(1024)
	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		x := eGetLine(scanner)
		y := eGetLine(scanner)
		fmt.Println(countLCS(x, y))
	}
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include <bits/stdc++.h>
       
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

int main() {
  int q;
  cin >> q;

  for (int i = 0; i < (int)(q); ++i) {
    string X, Y;
    cin >> X >> Y;

    int M = X.size(), N = Y.size();
    vector<vector<int>> dp(M + 1, vector<int>(N + 1, 0));
    for (int i = 0; i < (int)(M); ++i) for (int j = 0; j < (int)(N); ++j) {
      if (X[i] == Y[j]) chmax(dp[i + 1][j + 1], dp[i][j] + 1);
      chmax(dp[i + 1][j + 1], max(dp[i][j + 1], dp[i + 1][j]));
    }
    cout << dp[M][N] << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#define N 1000
using namespace std;

int lcs(string S1,string S2){
	int c[N+1][N+1];
	int S1_size = S1.size();
	int S2_size = S2.size();
	
	for(int i=1;i<S1_size;i++) c[i][0] = 0;
	for(int i=1;i<S2_size;i++) c[0][i] = 0;
	
	S1 = ' '+S1;
	S2 = ' '+S2;
	
	int max_lcs=0;
	for(int j=1;j<=S1_size;j++){
		for(int k=1;k<=S2_size;k++){
			if(S1[j]==S2[k]){
				c[j][k] = c[j-1][k-1] + 1;
			}else{
				c[j][k] = max(c[j-1][k],c[j][k-1]);
			}
			max_lcs = max(max_lcs,c[j][k]);
		}
	}
	return max_lcs;
}

int main() {
	// your code goes here
	int q;
	string str1,str2;
	cin>>q;
	for(int i=0;i<q;i++){
		cin>>str1>>str2;
		cout<<lcs(str1,str2)<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<cstring>
#include<cstdlib>
#define MAX_N 1000

int solve(std::string s,std::string t){
        int dp[MAX_N][MAX_N]={0};
        int n,m;
        n=s.size();
       m=t.size();
        for(int i=0;i<n;i++){
                for(int j=0;j<m;j++){
                        if(s[i]==t[j])
                                dp[i+1][j+1]=dp[i][j]+1;
                        else
                                dp[i+1][j+1]=max(dp[i][j+1],dp[i+1][j]);
                }
        }
        return dp[n][m];
}

int main(){
        int q;
        std::cin>>q;
        for(int i=0;i<q;i++){
                std::string s,t;
                std::cin >> s>>t;
                std::cout<<solve(s,t)<<std::endl;
        }
        return 0;
}

C++: #include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#define MAX 1001
void solve(void);
int q,count[MAX][MAX]={},xlength,ylength;
char X[MAX],Y[MAX];

void solve(void){
  int i,j;

  xlength=strlen(X);
  ylength=strlen(Y);
  
  for(i=1;i<=xlength;i++){
    for(j=1;j<=ylength;j++){
      if(X[i-1]==Y[j-1]) count[i][j]=count[i-1][j-1]+1;
      else if(count[i-1][j]>=count[i][j-1]) count[i][j]=count[i-1][j];
      else count[i][j]=count[i][j-1];
    }
  }
}
    
int main()
{
  int i;
  
  scanf("%d",&q);

  for(i=1;i<=q;i++){
    scanf("%s",X);
    scanf("%s",Y);
    solve();
    printf("%d\n",count[xlength][ylength]);
  }

  /*for(i=0;i<q;i++){
    printf("%d\n",count[][]);
    }*/

  return 0;
}

C++: import sys
sys.setrecursionlimit(10000)

def calc(x,y):
    i = len(x)
    j = len(y)
    if not d[i][j] == None:
        return d[i][j]
    else:
        if x[-1] == y[-1]:
            tmp = calc(x[:-1],y[:-1])+1
            d[i][j] = tmp
            return tmp
        else:
            tmp = max(calc(x[:-1],y),calc(x,y[:-1]))
            d[i][j] = tmp
            return tmp
        
q = int(input())
for i in range(q):
    x = input()
    y = input()
    d = [[0 if i == 0 or j == 0 else None for i in range(len(y)+1)] for j in range(len(x)+1)]
    print(calc(x,y))

C++: #include<iostream>
#include<cmath>
#include<algorithm>
#include<string>
using namespace std;
int dp[1001][1001];
int solve(string a,string b)
{	
	
	int maxn=0;
	int len1=a.size(),len2=b.size();
	

	for(int i=1;i<=len1;i++)
		for(int j=1;j<=len2;j++)
		{
			if(a[i-1]==b[j-1])
				dp[i][j]=dp[i-1][j-1]+1;
			else 
				dp[i][j]=max(dp[i-1][j],dp[i][j-1]);//这个只是表示某个状态的不是最大的，这个是自己设定的
			maxn=max(maxn,dp[i][j]);
		}
		return maxn;
		
		
	
}
int main()
{	int n;
	string a,b;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>a>>b;
		cout<<solve(a,b)<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;

int c[10001][10001];

int llcs(string X, string Y)
{
    //cout << "hhh" << endl;
    //cout << X << " " << Y << endl;
    int m=X.size();
    int n=Y.size();
    //cout << m << " " << n << endl;
    int maxl=0;
    X=' '+X;
    Y=' '+Y;

    for(int i=1;i<=m;i++)c[i][0]=0;
    for(int i=1;i<=n;i++)c[0][i]=0;


    for(int i=1;i<=m;i++)
    {
        for(int j=1;j<=n;j++)
        {
            //cout << i << " " << j << c[i][j] << endl;
            if(X[i]==Y[j]) c[i][j]=c[i-1][j-1]+1;
            else c[i][j]= max(c[i-1][j],c[i][j-1]);
            maxl=max(maxl,c[i][j]);
        }
    }
    return maxl;
}

int main()
{
    int N;
    cin >> N;
    string X,Y;
    for(int i=0;i<N;i++)
    {
        cin >> X;
        cin >> Y;
        cout << llcs(X,Y) << endl;
    }

    return 0;
}