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>
#include<algorithm>
using namespace std;

int lcs(string X, string Y){
  int c[1001][1001];
  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<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); ++i)

using namespace std;
using ll = long long;
using v1 = vector<int>;
using vl = vector<long long>;
using v2 = vector<vector<int>>;
using v3 = vector<vector<char>>;

int N, M;
string s1, s2;

int lcs(string x, string y){
	int c[1001][1001];
	N = s1.size();
	M = s2.size();
	int maxl = 0;
	x = ' ' + x;
	y = ' ' + y;
	rep(i, N) c[i][0] = 0;
	rep(i, M) c[0][i] = 0;
	for(int i = 1; i<=N;i++){
		for(int j = 1; j<=M; 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]);
		}
	}
	return maxl;
}

int main(){
	int n;
	cin >> n;
	rep(i, n){
		cin >> s1 >> s2;
		cout << lcs(s1,s2) << endl;
	}
}

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 = 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 - 1][j], c[i][j - 1]);
            }
            maxl = max(maxl, c[i][j]);
        }
    }

    return maxl;
}

int main(int argc, char const* argv[])
{
    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>
#define rep(i,n) for (int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int dp[1010][1010];

int main(){
    int q; cin >> q;
    rep(i,q){
        string x,y; cin >> x >> y;
        for(int i = 0; i < x.size(); i++){
            for(int j = 0; j < y.size(); j++){
                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[x.size()][y.size()] << endl;
    } 
    return 0;
}

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

/*int LCS(std::string str1, std::string str2, int i, int j){
  if(str1[i] == str2[j]){
    return 1;
  }
  else{
    return 0;
  }
 }
*/

int max(int a, int b, int c){
  int m = a;
  if(b > m){
    m = b;
  }
  if(c > m){
    m = c;
  }
  return m;
}

int main(){
  int q;
  std::cin >> q;
  //int ans[q];
  std::string str1, str2;
  for(int z=0; z<q; z++){
    std::cin >> str1 >> str2;
    int l1 = str1.size();
    int l2 = str2.size();
    int DP[l1+1][l2+1];

    for(int i=0; i<=l1; i++){
      DP[i][0] = 0;
    }
    for(int j=0; j<=l2; j++){
      DP[0][j] = 0;
    }

    for(int i=1; i<=l1; i++){
      for(int j=1; j<=l2; j++){
	if(str1[i-1] == str2[j-1]){
	  DP[i][j] = max(DP[i-1][j], DP[i][j-1], DP[i-1][j-1] + 1);
	}
	else{
	  DP[i][j] = max(DP[i-1][j], DP[i][j-1], DP[i-1][j-1]);
	}
      }
    }
    //ans[z] = DP[l1][l2];
    std::cout << DP[l1][l2] << std::endl;
  }

  /*for(int z=0; z<q; z++){
    std::cout << ans[z] << std::endl;
    }*/
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define INF 100000000000
const int MOD = 1000000009

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

// 最長共通部分列問題
// 入力
// S T

// dp[i + 1][j + 1] := Sのi文字目までと、Tのj文字目までのLCSの長さ
// 計算量 O(|S||T|)

int main(){

    //入力
    int n; cin >> n;
    for(int roop = 0; roop < n; roop++){
        string S, T; cin >> S >> T;
        vector<vector<int> > dp(S.size() + 1, vector<int> (T.size() + 1, INF));

        //dp初期条件
        dp[0][0] = 0;

        //dp
        for(int i = 0; i < S.size(); i++){
            for(int j = 0; j < T.size(); j++){
                if(S[i] == T[j]) dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j]);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i + 1][j]);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j + 1]);
            }
        }

        cout << dp[S.size()][T.size()];
        return 0;
    }
}

C++: #include <iostream>

using namespace std;

int lcs(string X, string Y) {
  int memo[1010][1010];
  // 初期化
  for (int i = 0; i < X.size(); i++) {
    memo[i][0] = 0;
  }
  for (int i = 0; i < Y.size(); i++) {
    memo[0][i] = 0;
  }
  int maxl = 0;
  int k = 0;
  for (int i = 0; i < X.size(); i++) {
    for (int j = 0; j < Y.size(); j++) {
      if (i <= 0 || j <= 0) {
        if (X[i] == Y[j]) {
          memo[i][j] = 1;
        } else {
          memo[i][j] = 0;
        }
      }
      else if (X[i] == Y[j]) {
        memo[i][j] = memo[i-1][j-1] + 1;
      } else {
        memo[i][j] = max(memo[i-1][j], memo[i][j-1]);
      }
      //cout << i << "," << j << "," << memo[i][j] << endl;
      maxl = max(maxl, memo[i][j]);
    }
  }
  return maxl;
}

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