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(){
	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>

using namespace std;

const int LEN = 1000;

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

    int c[LEN + 1][LEN + 1];

    string S, T;
    for (int i = 0; i < n; i++)
    {
        cin >> S;
        cin >> T;

        length = S.length() > T.length() ? S.length() : T.length();

        for (int j = 1; j < length+1; j++)
        {
            c[0][j] = c[j][0] = 0;
        }

        for (int j = 0; j < S.length(); j++)
        {
            for (int k = 0; k < T.length(); k++)
            {
                if (S[j] == T[k])
                {
                    c[j+1][k+1] = c[j][k] + 1;
                }
                else
                {
                    c[j+1][k+1] = c[j][k+1] > c[j+1][k] ? c[j][k+1] : c[j+1][k];
                }
            }
        }
        cout << c[S.length()][T.length()] << endl;
    }
}

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


void solve() {
    string s, t;
    cin >> s >> t;
    vector<vector<int> > dp(s.size(), vector<int>(t.size()));
    for (int i = 0; i < s.size(); i++) {
        for (int j = 0; j < t.size(); j++) {
            dp[i][j] = (i < 1 || j < 1 ? 0 : dp[i-1][j-1]) + (s[i] == t[j] ? 1 : 0);
            int a = (i < 1 ? 0 : dp[i-1][j]);
            int b = (j < 1 ? 0 : dp[i][j-1]);
            dp[i][j] = max(dp[i][j], max(a, b));
        }
    }

    cout << dp[s.size()-1][t.size()-1] << endl;
}

int main() {
    int n;
    cin >> n;
    while (n--) solve();

    return 0;
}

C++: #include<iostream>
#include<string>
int main()
{
  int n;
  int an[1000];
  int l=0;
  std::cin>>n;
  std::string x;
  std::string y;
  int ans[1001][1001];
  int j,k;
  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<=1000;j++){
      for(int k=0;k<=1000;k++){
	ans[j][k]=0;
      }
    }
    for(int j=0;j<=x.size();j++){
      for(int k=0;k<=y.size();k++){
	if(x[j-1]==y[k-1]){
	  ans[j][k]=ans[j-1][k-1]+1;
	}else{
	  if(ans[j][k-1]>ans[j-1][k]){
	    ans[j][k]=ans[j][k-1];
	  }else{
	    ans[j][k]=ans[j-1][k];
	  }
	}
      }
    }
    std::cout<<ans[x.size()-1][y.size()-1]<<'\n';  
  }
  return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;
#define len(n) (int)n.length()
#define pb push_back
#define ll long long
#define make_pair mkp
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define ALL(v) (v).begin(), (v).end()
#ifdef DBGPRT
#define dbg(n) cerr << "//" << #n << ":" << n <<endl
#else
#define dbg(n) ;
#endif
typedef pair<ll, ll> LLARR;
#define INF 999999999
const double PI = 3.1415926535897932384626433832795;

ll lcs(string s1, string s2)
{
	int m = len(s1);
	int n = len(s2);
	s1 = ' '+s1;
	s2 = ' '+s2;
	int (*mat)[1001];
	mat = new int[1001][1001];
	REP(i, m)
	{
		mat[i][0] = 0;
	}
	REP(i, n)
	{
		mat[0][i] = 0;
	}
	int maxx = 0;
	FOR(i, 1, m+1)
	{
		FOR(j, 1, n+1)
		{
			if (s1[i] == s2[j])
				mat[i][j] = mat[i-1][j-1] + 1;
			else
				mat[i][j] = max(mat[i][j-1], mat[i-1][j]);
			maxx = max(maxx, mat[i][j]);
		}
	}
	delete[] mat;
	return maxx;
}
int main()
{
	ios::sync_with_stdio(false);

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

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

int main(){
    int Q;
    string str_x, str_y;
    int memo[1001][1001];
    cin >> Q;
    
    for(int q = 0;q < Q;q++){
        cin >> str_x >> str_y;
        
        for(unsigned int i = 0;i < str_x.size();i++){
            for(unsigned int j = 0;j < str_y.size();j++){
                if(str_x.at(i) == str_y.at(j)){
                    memo[i+1][j+1] = memo[i][j] + 1;
                }else{
                    memo[i+1][j+1] = max(memo[i][j+1], memo[i+1][j]);
                }
            }
        }
        
        printf("%d\n", memo[str_x.size()][str_y.size()]);
    }
    
    return 0;
}

C++: #include <iostream>

int lcs(std::string x, std::string y)
{
  int m = x.length();
  int n = y.length();
  int cs[m + 1][n + 1];

  for (int i = 0; i < m + 1; ++i)
    cs[i][0] = 0;
  for (int j = 1; j < n + 1; ++j)
    cs[0][j] = 0;

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

  return cs[m][n];
}

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

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

  return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <stack>
#include <algorithm>
#include <iostream>
#include <string>
#include <map>
#include <queue>
#include <stdio.h>
#include <math.h>


using namespace std;

typedef long long ll;

typedef vector<vector<int>> vvi;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<ll> vll;

typedef pair<int, int> P;

typedef queue<int> qi;
typedef queue<string> qs;


#define rep(i, n) for(int i=0; i<(n); ++i)
#define repp(i, a, b) for(int i = (a); i <= (b); i++)
#define Rep(i, n) for(int i=n; i >= 0; i--)

#define all(v) v.begin(), v.end()
//sort( all(v) )　などと使える

const int INF = 50010;

int main() {
	int q; cin >> q;
	rep(i, q) {
		string x, y; cin >> x >> y;
		int n = x.size(), m = y.size();

		vvi dp(n + 1, vi(m + 1, 0));

		rep(i, n) rep(j, m) {
			if (x[i] == y[j]) dp[i + 1][j + 1] = dp[i][j] + 1;
			else dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
		}

		cout << dp[n][m] << endl;
	}
}