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 <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); i++)
#define loop(i, a, n) for(int i = (a); i < (n); i++)
using namespace std;
using ll = int64_t;

int main(){
    int q; cin >> q;
    rep(qi, q){
        string x, y; cin >> x >> y;
        int xsize = x.size(), ysize = y.size();
        int dp[xsize+1][ysize+1];
        memset(dp, 0, sizeof(dp));
        loop(i, 1, xsize+1)loop(j, 1, ysize+1){
            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]);
        }
        cout << dp[xsize][ysize] << endl;
    }

    return 0;
}

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

int dp[1002][1002];

int main()
{
	for (int i = 0; i < 1002; i++)
	{
		dp[0][i] = 0;
		dp[i][0] = 0;
	}
	int N;
	cin >> N;
	for (int i = 0; i < N; i++)
	{
		string str1, str2;
		cin >> str1 >> str2;
		for (int i = 1; i <= str1.size(); i++)
		{
			for (int j = 1; j <= str2.size(); j++)
			{
				if (str1[i - 1] == str2[j - 1])dp[i][j]=dp[i - 1][j - 1] + 1;
				else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
			}
		}
		cout << dp[str1.size()][str2.size()] << endl;
	}
	return 0;
}

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

int dp[1001][1001];
string str1, str2;
int n;

int solve(string str1, string str2) {
  memset(dp, 0, sizeof(dp));
  for(int r = 0; r < str2.size(); r++) {
    for(int c = 0; c < str1.size(); c++) {
      if(str2[r] == str1[c]) {
        dp[r + 1][c + 1] = dp[r][c] + 1;
      }
      else {
        dp[r + 1][c + 1] = max(dp[r + 1][c], dp[r][c + 1]);
      }
    }
  }
  return dp[str2.size()][str1.size()];
}

int main() {
  cin >> n;
  for(int i = 0; i < n; i++) {
    cin >> str1 >> str2;
    cout << solve(str1, str2) << endl;
  }
}

C++: #include <cmath>
#include <cstdlib>
#include <iostream>
#include <bitset>
#include <deque>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <vector>
#include <algorithm>
#include <iterator>
#include <string>
#include <chrono>
#include <random>
#include <tuple>
#include <utility>
#include <fstream>

std::string x, y;
long cnt[1005][1005];//[i][j]: x[i], y[j]までの和
long q;

int main(){
	scanf("%ld", &q);
	for(int i = 0; i < q; i++){
		std::cin >> x >> y;
		for(int i = 0; i <= x.length(); i++){
			for(int j = 0; j <= y.length(); j++){
				if(i == 0 || j == 0){
					cnt[i][j] = 0;
				}else if(x[i-1] == y[j-1]){
					cnt[i][j] = cnt[i-1][j-1] + 1;
				}else{
					cnt[i][j] = std::max(cnt[i-1][j], cnt[i][j-1]);
				}
			}
		}
		printf("%ld\n", cnt[x.length()][y.length()]);
	}
	return 0;
}

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

using namespace std;
using ll = long long;

void init();
void solve();

#define rep(i, a) for (int i = 0; i < (int) (a); i++)
#define reps(i, a, b) for (int i = (int) (a); i < (int) (b); i++)
#define rrep(i, a) for (int i = (int) a-1; i >= 0; i--)
#define rreps(i, a, b) for (int i = (int) (a)-1; i >= (int) (b); i--)
#define MP(a, b) make_pair((a), (b))
#define PB(a) push_back((a))
#define all(v) (v).begin(), (v).end()
#define PRINT(f) if((f)){cout << (TRUE__) << endl;}else{cout << FALSE__ << endl;}
#define TRUE__  "Yes"
#define FALSE__ "No"
#define PERM(v) next_permutation(all(v))
#define UNIQUE(v) sort(all(v));(v).erase(unique(all(v)), v.end())
#define CIN(type, x) type x;cin >> x

#ifdef LOCAL
#define lcout(a) cout << a
#define lcoutln(a) cout << a << endl
#define lcerr(a) cerr << a
#define lcerrln(a) cerr << a << endl
#else
#define lcout(a) 
#define lcoutln(a) 
#define lcerr(a) 
#define lcerrln(a) 
#endif
#define MOD 1000000007

signed main()
{
	init();
	solve();
}

int q, xl, yl;
string x, y;

void init()
{
	cin >> q;
}

int dp[1010][1010];

void reset()
{
	rep(i, 1010) {
		dp[i][0] = 0;
		dp[0][i] = 0;
	}
}


void solve()
{
	rep(i, q) {
		cin >> x >> y;
		xl = x.length();
		yl = y.length();
		reps(i, 1, xl+1) reps(j, 1, yl+1) {
			if (x[i-1] == y[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
			else dp[i][j] = max(dp[i][j-1], dp[j-1][i]);
		}
		cout << dp[xl][yl] << endl;
		reset();
	}
}

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

int main(){
  int INF=-10000;

  int d;
  int i,j,k;
  cin>>d;
  vector<int> ans(d);
  for(k=0;k<d;k++){
    string a,b;
    cin>>a>>b;

    vector<vector<int>> dp(a.size()+1,vector<int>(b.size()+1,0));
    dp.at(0).at(0)=0;
    for(i=0;i<a.size();i++){
      // cout<<"i "<<i<<endl;
      for(j=0;j<b.size();j++){
        // cout<<"j "<<j<<endl;
        if(a.at(i)==b.at(j)){
          dp.at(i+1).at(j+1)=dp.at(i).at(j)+1;
        } else{
          dp.at(i+1).at(j+1)=max(dp.at(i).at(j+1),dp.at(i+1).at(j));
        }
      }
    }

    ans.at(k)=dp.at(a.size()).at(b.size());
}

for(k=0;k<d;k++)
cout<<ans.at(k)<<endl;

}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int dp[1001][1001];
string s,t;
int n,m,a,ans;
int main(){
  cin>>a;
  for(int b=0;b<a;b++){
    cin>>s>>t;
    for(int i=0;i<=1000;i++)
      for(int j=0;j<=1000;j++)
	dp[i][j]=0;
    m=s.size();
    n=t.size();
    ans=0;
    for(int i=1;i<=m;i++){
      for(int j=1;j<=n;j++){
	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]);
	}
      }
    }  
    cout<<dp[m][n]<<endl;
  }
  return 0;
}

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

using namespace std;

int q;
int main() {
	cin >> q;
	for (int i = 0; i < q; i++) {
		string x, y;
		cin >> x >> y;
		int m = x.size();
		int n = y.size();
		x = ' ' + x;
		y = ' ' + y;
		int maxl = 0;
		int c[1001][1001];
		c[0][0] = 0;
		for (int i = 1; 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][j - 1], c[i - 1][j]);
				}
				maxl = max(maxl, c[i][j]);
			}
		}
		cout << maxl << endl;
	}
	return 0;
}