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 <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 <iostream>
#include <string>
#include <algorithm>
using namespace std;
#define N (1000)
int lcs(string X,string Y){
    int c[N+1][N+1];
    int m=X.size();
    int n=Y.size();
    int maxv=0;
    X=' '+X;
    Y=' '+Y;
    for(int i=0;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++){
            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]);
            }
            maxv=max(maxv,c[i][j]);
        }
    }
    return maxv;
}

int main(void){
    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;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

int dp[1001][1001];
int main(){
    int n;
    string s,t;
    cin>>n;
    rep(i,n){
        cin>>s>>t;
        memset(dp,0,sizeof(dp));
        int ss=s.size(),st=t.size();
        rep(i,ss){
            rep(j,st){
                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]);
                }
            }
        }
        cout<<dp[ss][st]<<endl;
    }
    return 0;
}

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

int dp[150+1][150+1];

int lcsSub(std::string X, std::string Y, int i, int j){
	if (i==-1 || j==-1){
		return 0;
	}
	else{
		if(X[i]==Y[j]){
			if (dp[i][j] < 0){
				dp[i][j] = lcsSub(X, Y, i-1, j-1);
			}
			return dp[i][j]+1;
		}
		else{
			int up, left;
			if (dp[i+1][j] < 0){
				dp[i+1][j] = lcsSub(X, Y, i, j-1);
			}
			left = dp[i+1][j];
			if (dp[i][j] < 0){
				dp[i][j+1] = lcsSub(X, Y, i-1, j);
			}
			up = dp[i][j+1];
			
			return std::max(up, left);
		}
	}
}

int lcs(std::string X, std::string Y){
	int m,n,i,j;
	m = X.length();
	n = Y.length();
	for(i=0;i<m+1;i++){
		for(j=0;j<n+1;j++){
			dp[i][j] = -1;
		}
	}
	return lcsSub(X, Y, m-1, n-1);
}
int main(void){
	int i,q,n,m;
	std::string str1, str2;
	std::cin >> q;
	for (i=0;i<q;i++){
		std::cin >> str1;
		std::cin >> str2;
		std::cout << lcs(str1, str2) << std::endl;
	}
	return 0;
}

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

int main(){
    int q;
    for(int i = 0; i < q; i++){
        string S1, S2;
        cin >> S1 >> S2;
        const int m = S1.size();
        const int n = S2.size();
        int dp[m][n] = {0};
        for(int j = 0; j < m; j++){
            for(int k = 0; k < n; k++){
                if(j == 0 && k == 0);
                else if(j == 0) dp[j][k] = dp[j][k-1];
                else if(k == 0) dp[j][k] = dp[j-1][k];
                else{
                    dp[j][k] = max(dp[j-1][k],dp[j][k-1]);
                }
                if(S1[j] == S2[k]) dp[j][k]++;
            }
        }
        cout << dp[m-1][n-1] << endl;
    }
}

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

#define MAX_SIZE 1010

int lcm(string X, string Y) {
    int c[MAX_SIZE][MAX_SIZE];
    int m = X.size(), n = Y.size();
    X = ' ' + X;
    Y = ' ' + Y;
    for (int i = 0; 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++) {
            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]);
        }
    }

    return c[m][n];
}

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

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<string>
#include<cstring>
#define maxn 1005
using namespace std;

int dp[maxn][maxn];
int len1, len2;
string s1, s2;

int lcs()
{
	memset(dp, 0, sizeof(dp));
	for(int i=1;i<=len1;i++)
		for (int j = 1; j <= len2; j++)
		{
			if (s1[i] == s2[j]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			}
			else
			{
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
			}
		}
	return dp[len1][len2];
}

int main()
{
	int n;
	cin >> n;
	while (n--)
	{
		cin >> s1 >> s2;
		len1 = s1.size(), len2 = s2.size();
		s1 = ' ' + s1;
		s2 = ' ' + s2;
		cout << lcs() << endl;
	}
	return 0;
}

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

#define FOR( i, m, n )  for( int (i) = (m); (i) < (n); (i)++ )
#define REP( i, n )     FOR( i, 0, n )
#define ALL( a )        (a).begin(), (a).end()             

int	dp[1001][1001] = {};

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

	int maxl;

	string s1, s2;
	REP( i, n ) {
		cin >> s1 >> s2;
		maxl = 0;
		memset( dp, 0, sizeof( int ) );
		FOR( j, 1, s1.size() + 1 ) {
			FOR( k, 1, s2.size() + 1 ) {
				if( s1[j] == s2[k] ) {
					dp[j][k] = dp[j - 1][k - 1] + 1;
				} else {
					dp[j][k] = max( dp[j - 1][k], dp[j][k - 1] );
				}
				maxl = max( dp[j][k], maxl );
			}
		}

		cout << maxl << endl;
	}
}