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 <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <string>
#include <climits>
#include <tuple>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef tuple< int,int,int > T;
const int MAX_N=55555;
bool is_prime[MAX_N];
int prime[MAX_N];
int main(){
  int n;
  cin>>n;
  int dp[1001][1001];
  for(int nn=0;nn<n;nn++){
    string s1,s2;
    cin>>s1>>s2;
    for(int i=0;i<1001;i++)fill(dp[i],dp[i]+1001,0);
    for(int i=0;i<s1.size();i++){
      for(int j=0;j<s2.size();j++){
        if(s1[i]==s2[j]) dp[i+1][j+1]=max(dp[i][j]+1,max(dp[i][j+1],dp[i+1][j]));
        else dp[i+1][j+1]=max(dp[i+1][j],dp[i][j+1]);
      }
    }
    cout<<dp[s1.size()][s2.size()]<<endl;
  }
  return 0;
}

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

vector<vector<int>> c(1001,vector<int>(1001));

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

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

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

using namespace std;

int main(){
  string X,Y;
  int n;
  cin>>n;
  for(int m=0;m<n;m++){
  cin>>X>>Y;

  int N[X.size()+1][Y.size()+1];

  for(int i=0;i<=X.size();i++){
    for(int j=0;j<=Y.size();j++){

      N[i][j]=1;
}
  }

  /*
  for(int i=0;i<X.size();i++){
    cout<<X[i]<<endl;
  }

for(int i=0;i<Y.size();i++){
    cout<<Y[i];
  }
  */

  
for(int i=0;i<=X.size();i++){
  N[i][0]=0;
  }

for(int i=0;i<=Y.size();i++){
  N[0][i]=0;
  }

 int point;

  for(int i=1;i<=X.size();i++){
    for(int j=1;j<=Y.size();j++){
      if(X[i-1]==Y[j-1]){
	point=1;
	
      }else{
	point=0;
      }
       N[i][j]=max({N[i-1][j],N[i][j-1],N[i-1][j-1]+point});
       point=0;
}
   
  }

  cout<<N[X.size()][Y.size()];
  /*
  //answer
  for(int i=0;i<=X.size();i++){
    for(int j=0;j<=Y.size();j++){

      cout<<N[i][j]<<" ";
      if(j==Y.size()){
	cout<<endl;
      }
}
  }
  */

  }

}

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

#ifdef DEBUG

#define printd printf

#else

#define printd(...)

#endif


int lcs(std::string &x, std::string &y) {
    static int dp[1002][1002];

    for (int i = 0; i < x.length() + 2; i++) {
        for (int j = 0; j < y.length() + 2; j++) {
            dp[i][j] = 0;
        }
    }

    for (int i = 1; i <= x.length(); i++) {
        for (int j = 1; j <= y.length(); j++) {
            if (x[i - 1] == y[j - 1]) {
                dp[i][j] = std::max(dp[i - 1][j - 1] + 1, dp[i - 1][j]);
                dp[i][j] = std::max(dp[i][j], dp[i][j - 1]);
            } else {
                dp[i][j] = std::max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
    }

    #ifdef DEBUG
    for (int i = 1; i <= x.length(); i++) {
        for (int j = 1; j <= y.length(); j++) {
            std::cout << dp[i][j] << ", ";
        }
        std::cout << std::endl;
    }
    #endif

    return dp[x.length()][y.length()];
}

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

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

    return 0;
}