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<cstdlib>
#include<cmath>
#include<vector>
#include<list>
#include<map>
#include<algorithm>

using namespace std;

int solve(string x, string y)
{
    vector<vector<int> > c(x.size(), vector<int>(y.size(), 0));

    if (x[0] == y[0]) {
        c[0][0] = 1;
    }

    for (int i = 1; i < x.size(); i++) {
        if (c[i - 1][0] == 1 || x[i] == y[0]) {
            c[i][0] = 1;
        } else {
            c[i][0] = 0;
        }
    }
    for (int i = 1; i < y.size(); i++) {
        if (c[0][i - 1] == 1 || x[0] == y[i]) {
            c[0][i] = 1;
        } else {
            c[0][i] = 0;
        }
    }

    for (int i = 1; i < x.size(); i++) {
        for (int j = 1; j < y.size(); 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[x.size() - 1][y.size() - 1];
}

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

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

    return 0;
}

C++: #include<iostream>
#include<string>
using namespace std;
int L[1001][1001];
int main(){
    int N;
    string X,Y;
    cin >>N;
    for(int k=0;k<N;++k){
        cin>>X>>Y;
        for(int i=1;i<X.length()+1;++i){
            for(int j=1;j<Y.length()+1;++j){
                if(X[i]==Y[j]){
                    L[i][j]=L[i-1][j-1]+1;
                }
                else
                    L[i][j]=max(L[i-1][j],L[i][j-1]);
                
            }
        }
        cout<<L[X.length()][Y.length()]<<endl;
    }
    return 0;
}

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

int main(){
  int n;
  char x[1000],y[1000];
  int dp[1001][1001];
  //load n;
  cin >>n;
  for(int i=0;i<n;i++){
    //load string
    scanf("%s",x);
    scanf("%s",y);
    //dp
    for(int j=0;j<strlen(x);j++){
      for(int k=0;k<strlen(y);k++){
	if(x[j]==y[k]){
	  dp[j+1][k+1]=dp[j][k]+1;
	}

	else{
	  if(dp[j][k+1]>dp[j+1][k]){
	    dp[j+1][k+1]=dp[j][k+1];
	  }

	  else{
	    dp[j+1][k+1]=dp[j+1][k];
	  }


	}
      }
    }
    cout <<dp[strlen(x)][strlen(y)]<<endl;
  }



  return 0;
}

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

#define N 1001
int A[N][N];

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

    string target1;
    string target2;
    for (int i = 0; i < q; i++) {
        cin >> target1;
        cin >> target2;
        int l1 = target1.length();
        int l2 = target2.length();
        for (int m = 0; m <= l1; m++) {
            A[m][0] = 0;
        }
        for (int n = 0; n <= l2; n++) {
            A[0][n] = 0;
        }

        target1 = ' ' +  target1;
        target2 = ' ' +  target2;

        for (int m = 1; m <= l1; m++) {
            for (int n = 1; n <= l2; n++) {
                if (target1[m] == target2[n]) {
                    A[m][n] = A[m-1][n-1] + 1;
                } else {
                    A[m][n] = max(A[m-1][n], A[m][n-1]);
                }
            }
        }

        cout << A[l1][l2] << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>

#define iter(n) for(int iter_var = 0; iter_var < n; iter_var += 1)
#define rep(i, s, n) for(int i = s; i < n; i += 1)
#define lli long long int
#define INF 1e9
#define MOD 1000000007

using namespace std;

int lcs(string s, string t){

  int s_size = s.size();
  int t_size = t.size();
  vector<vector<int>> dp(s_size + 1, vector<int>(t_size + 1, 0));

  rep(i, 1, s_size + 1) rep(j, 1, t_size + 1){
    if(s[i - 1] == t[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[s_size][t_size];
}

int main(){

  int n; cin >> n;
  iter(n){
    string s, t; cin >> s >> t;
    cout << lcs(s, t) << endl;
  }

  return 0;
}