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])
	}
}

C++: #include<iostream>
#include<stdio.h>
//#include <bits/stdc++.h>
#include<vector>
#include<float.h>
#include<iomanip>
#include<algorithm>
#include<string>
#include<cstring>
#include<math.h>
#include<cmath>
#include<sstream>
#include<set>
#include<map>
#include<queue>
#include <cassert>
#include <cmath>
#include<cstdint>

#define INF 1e9
#define rep(i,n)for(int i=0;(i)<(int)(n);i++)
#define REP(i,a,b)for(int i=(int)(a);(i)<=(int)(b);i++)
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define vec(type,n) vector<type>(n)
#define vvec(m,n) vector<vector<int>> (int(m),vector<int>(n))
#define ALL(a)  (a).begin(),(a).end()

using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
using P = pair<int,int>;

vector<int>bitSearch(int bit,int n){
    vector<int>S;
    rep(i,n)if(bit&(1<<i))S.push_back(i);
    return S;
}

int main(){
    int q;
    while(cin>>q){
        rep(i,q){
            string s,t;cin>>s>>t;
            int m = s.size(),n = t.size();
            s.insert(0,"0");
            t.insert(0,"0");
            int dp[m+1][n+1];
            rep(j,m+1)rep(k,n+1)dp[j][k] = 0;
            REP(j,1,m){
                REP(k,1,n){
                    if(s[j] == t[k]){
                        dp[j][k] = max({dp[j][k],dp[j-1][k-1]+1,dp[j-1][k],dp[j][k-1]});
                    }
                    else dp[j][k] = max({dp[j][k],dp[j-1][k],dp[j][k-1]});
                }
            }
            cout<<dp[m][n]<<endl;
        }
    }
}

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

int main(int argc, char const *argv[]) {
        int x; cin>>x;

        while (x--) {
                string s,t; cin>>s>>t;
                int n = s.length(); int m = t.length();
                vector<vector<int> > dp(n+1, vector<int>(m+1, 0));
                for (int i = 1; i <= n; ++i) {
                        for (int j = 1; j <= m; j++) {
                                if (s[i-1]==t[j-1]) dp[i][j] = max(dp[i][j], dp[i-1][j-1]+1);
                                else {
                                        dp[i][j] = max(dp[i][j], max(dp[i-1][j], dp[i][j-1]));
                                }
                        }
                }
                cout << dp[n][m] << endl;
        }

        return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int main() {
  int q; cin >> q;
  string A, B; cin >> A >> B;
  for (int i=0; i<q; i++) {
    vector<vector<int>> LCS(A.length()+1, vector<int>(B.length()+1,0));
    for (int j=1; j<=A.length(); j++) {
      for (int k=1; k<=B.length(); k++) {
        if(A[j]==B[k]) LCS[j][k]=LCS[j-1][k-1]+1;
        else LCS[j][k] = max(LCS[j-1][k],LCS[j][k-1]);
      }
    }
    cout << LCS[A.length()][B.length()]
  }
}

C++: #include <bits/stdc++.h>
using namespace std;
long long dp[1002][1002];
int main() {
  int n;cin>>n;
  for(int i=0; i<n; i++){
  
  string a,b; cin>>a>>b;
  int al=a.size(); int bl=b.size();
  for (int i=0;i<1002;i++){for(int j=0;j<1002;j++){dp[i][j]=0;}}
  for (int j=0;j<al;j++){
  for (int k=0;k<bl;k++){
  if(a[j]==b[k]){dp[j+1][k+1]=dp[j][k]+1;}
  else{dp[j+1][k+1]=max(dp[j+1][k],dp[j][k+1]);}
  }
  }
  cout << dp[al][bl] << endl;
  }
}

C++: #include<iostream>
#include<vector>
#include<string>
using namespace std;
string s1,s2;
int memo[100][100];

int solve(int l1,int l2){
  if(memo[l1][l2] < 0)return memo[l1][l2];
  if(l1 < 0 or l2 < 0)return 0;
  //cout << s1[l1] << s2[l2] << endl;
  if(s1[l1] == s2[l2]){
    return memo[l1][l2] = solve(l1 - 1,l2 - 1) + 1;
  }
  return memo[l1][l2] = max(solve(l1,l2-1), solve(l1-1,l2));
}
int main(){
  int n;
  cin >> n;
  for(int i = 0;i < n;i++){
    fill(*memo,*(memo+100),-1);
    cin >> s1 ;
    cin >> s2;
    cout << solve(s1.length(),s2.length()) - 1 << endl;
  }
}

C++: #include <iostream>
#include <cmath>
#define MAX_NUMBER 1001

using namespace std;

int main () {
  // 最长公共子序列
  int n;
  string x, y;
  int lcs, c[MAX_NUMBER][MAX_NUMBER];

  cin >> n;

  for (int k = 0; k < n; k++) {
    cin >> x;
    cin >> y;

    x = " " + x;
    y = " " + y;
    lcs = 0;
    for (int i = 0; i < MAX_NUMBER; i++)
      for (int j = 0; j < MAX_NUMBER; j++)
        c[i][j] = 0;
    
    for (int i = 1; i < x.length(); i++) {
      for (int j = 1; j < y.length(); j++) {
        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]);
      }
    }

    cout << c[x.length() - 1][y.length() - 1] << endl;
  }

  return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
char s1[1005];
char s2[1005];
int chang[1005][1005];
int main(){
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        scanf("%s%s",s1,s2);
        int sl1=strlen(s1);
        int sl2=strlen(s2);
        for(int i=0;i<=sl1;i++){
                chang[i][0]=0;
        }
        for(int i=0;i<=sl2;i++){
                chang[0][i]=0;
        }
        for(int i=1;i<=sl1;i++){
            for(int j=1;j<=sl2;j++){
                if(s1[i]==s2[j]){
                    chang[i][j]=chang[i-1][j-1]+1;
                }
                else {
                    chang[i][j]=max(chang[i-1][j],chang[i][j-1]);
                }
            }
        }
        printf("%d\n",chang[sl1][sl2]);
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define For(I,A,B) for(int I=(A); I < (B); ++I)
int c[1005][1005];
int main()
{
int t;
string p;
cin>>t;
getline(cin,p);
while(t--){

int x,y,z,k=0,l,i,j;
string a,b;

 For(i,0,1005)
 For(j,0,1005)
 c[i][j]=0;

 getline(cin,a);
 getline(cin,b);
 x=a.length();
 y=b.length();

 For(i,1,x+1)
 For(j,1,y+1)
 {
     if(a[i-1]==b[j-1]) c[i][j]=c[i-1][j-1]+1;
     else  c[i][j]=max(c[i-1][j],c[i][j-1]);
 }
    cout<<c[x][y]<<endl;

}

    return 0;
}