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 <cstdio>
#include <iostream>
#include <string>
using namespace std;

int main(){
	int q;
	scanf(" %d", &q);
	for(int i=0; i<q; ++i){
		string a, b;
		cin >> a >> b;
		
		int m=a.size(), n=b.size();
		
		string x=" "+a;
		string y=" "+b;
		
		int c[1001][1001]={0};
		for(int i=1; i<=m; ++i) c[i][0]=0;
		for(int i=1; i<=n; ++i) c[0][n]=0;
		
		int ans=0;
		for(int i=1; i<=m; ++i){
			for(int j=1; j<=n; ++j){
				if(x[i]==y[j]) c[i][j]=c[i-1][j-1]+1;
				else c[i][j]=max(c[i][j-1], c[i-1][j]);
				
				ans=max(ans,c[i][j]);		
			}
		}
		
		printf("%d\n", ans);
	}
}

C++: #include <iostream>
#include <string>

#define MAX_N 1000
#define MAX_M 1000

int n, m;
std::string s, t;

int dp[MAX_N+1][MAX_M+1];

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

int main() {
  int q;
  std::cin >> q;
  for (int i = 0; i < q; ++i) {
    std::cin >> s >> t;
    n = s.size();
    m = t.size();
    solve();
    std::cout << dp[n][m] << std::endl;
  }
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
static const int N =1000;

int lcs(string X,string Y){
  int c[N+1][N+1];
  int m=X.size();
  int n=Y.size();
  int maxl=0;
  X=' '+X;
  Y=' '+Y;
  for(int i=0;i<=m;i++)c[i][0]=0;
  for(int j=1;j<=n;j++)c[0][j]=0;

  for(int i=1;i<=m;i++){
    for(int j=1;j<=n;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]);
      }
maxl=max(maxl,c[i][j]);
    }
  }
return maxl;
}

int main(){
  string s1,s2;
  int n;cin>>n;
  for(int i=0;i<n;i++){
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<endl;
  }
return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int a[1003][1003];
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        string x,y;
        cin>>x>>y;
        int len1=x.size();
        int len2=y.size();

        memset(a,0,sizeof(a));
        for(int i=0; i<len1; i++)
        {
            for(int j=0; j<len2; j++)
            {
                if(x[i]==y[j])
                {
                    a[i+1][j+1]=a[i][j]+1;
                }
                else a[i+1][j+1]=max(a[i][j+1],a[i+1][j]);
            }
        }
        cout<<a[len1][len2]<<endl;
    }

}

C++: #include <iostream>
#include <algorithm>

using namespace std;

int LCSLength(string X, string Y){
    int m = X.size();
    int n = Y.size();
    int c[m+1][n+1];
    int maxLength = 0;
    for(int i = 1; i <= m; i++) c[i][0] = 0;
    for(int j = 0; j <= n; j++) c[0][j] = 0;
    for(int i = 1; i <= m; i++){
        for(int j = 1; j <= n; j++){
            if(X[i] == Y[j]) c[i][j] = c[i-1][j-1] + 1;
            else if(c[i-1][j] >= c[i][j-1]) c[i][j] = c[i-1][j];
            else c[i][j] = c[i][j-1];
            maxLength = max(maxLength, c[i][j]);
        }
    }
    return maxLength;
}

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

C++: #include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

int lcs(string x, string y) {
    int lx = x.size(), ly = y.size();
    vector<vector<int>> dp(lx+1, vector<int>(ly+1, 0));
    for (int i=1;i<=lx; i++){
        for (int j=1; j<=ly; j++){
            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[lx][ly];
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(0);

    int q;
    cin >> q;
    for (int i=0;i<q;i++) {
        string x, y;
        cin >> x >> y;
        cout << lcs(x, y) << endl;
    }

    return 0;
}

C++: #include<string>
int lcs(std::string s, std::string t) {
    const int M = s.size(), N = t.size();
    int dp[M+1][N+1] = {};
    for(int i=0; i<M; ++i)
        for(int j=0; j<N; ++j)
            if(s[i] == t[j]) dp[i+1][j+1] = dp[i][j] + 1;
            else dp[i+1][j+1] = std::max(dp[i+1][j], dp[i][j+1]);
    return dp[M][N];
}
#include<iostream>
using namespace std;
int main(){
    int n;
    cin>>n;
    for(int i=0;i<n;++i){
        string s,t;
        cin>>s>>t;
        cout<<lcs(s,t)<<endl;
    }
}

C++: #include <stdio.h>
#include <iostream>
#include <utility>
#include <algorithm>
#include <math.h>
#include <vector>
using namespace std;
int dp[1001][1001] = {};

int getLCS(string X, string Y)
{
    for (int i = 1; i <= X.size(); i++)
    {
        for (int j = 1; j <= Y.size(); j++)
        {
            dp[i][j] = X[i - 1] == Y[j - 1] ? dp[i - 1][j - 1] + 1 : max(dp[i - 1][j], dp[i][j - 1]);
        }
    }
    return dp[X.size()][Y.size()];
}

int main()
{
    int q;
    string X, Y;
    cin >> q;
    for (int i = 0; i < q; i++)
    {
        cin >> X >> Y;
        cout << getLCS(X, Y) << "\n";
    }
    return 0;
}