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 = 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(){
  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<stdio.h>
??
int LCS(char x[], char y[]) {
????int xn = 0, yn = 0, flag = 0, i, j, max = 0;
????int c[1001][1001];
??????
????while (flag == 0)
????{
????????if (x[xn] != '\0')
????????{
????????????xn++;
????????}
????????else
????????{
????????????flag = 1;
????????}
????}
??????
????flag = 0;
??????
????while (flag == 0)
????{
????????if (y[yn] != '\0')
????????{
????????????yn++;
????????}
????????else
????????{
????????????flag = 1;
????????}
????}
????for (i = 1; i < xn + 1; i++) c[i][0] = 0;
????for (j = 1; j < yn + 1; j++) c[0][j] = 0;
??????
????for (i = 1; i < xn + 1; i++)
????{
????????for (j = 1; j < yn + 1; j++)
????????{
????????????if (x[i - 1] == y[j - 1])
????????????{
????????????????c[i][j] = c[i - 1][j - 1] + 1;
????????????}
????????????else if (c[i - 1][j] >= c[i][j - 1])
????????????{
????????????????c[i][j] = c[i - 1][j];
????????????}
????????????else
????????????{
????????????????c[i][j] = c[i][j - 1];
????????????}
????????????if (max < c[i][j]) max = c[i][j];
????????}
????}
??????
????return max;
}
??
int main(void) {
????char x[1000], y[1000];
????int q, i;
??????
????scanf("%d", &q);
??????
????for (i = 0; i < q; i++)
????{
????????scanf("%s", x);
????????scanf("%s", y);
????????printf("%d\n", LCS(x, y));
????}
??????
????return 0;
}

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;
}

signed main() {
  int n; cin >> n;
  for(int i = 0; i < n; i++) {
    string s1, s2;
    cin >> s1 >> s2;
    cout << lcs(s1, s2) << endl;
  }
  return 0;
}

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

string a, b;
int q;
// iまで、jまででの答え
int dp[1005][1005] = {0};

int solve();

int main() {
  cin >> q;
  for(int qq = 0; qq < q; ++qq) {
    cin >> a >> b;
    cout << solve() << endl;
    for(int i = 1; i <= a.size(); ++i)
      for(int j = 1; j <= b.size(); ++j) dp[i][j] = 0;
  }
  return 0;
}

int solve() {
  for(int i = 1; i <= a.size(); ++i)
    for(int j = 1; j <= b.size(); ++j) {
      dp[i][j] =
          max(dp[i][j - 1],
              max(dp[i - 1][j - 1] + (a[i - 1] == b[j - 1]),
                  dp[i - 1][j]));
    }
  return dp[a.size()][b.size()];
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <set>
#include<algorithm>
#include <iomanip>
int ctoi(char c) {
	switch (c) {
	case '0': return 0;
	case '1': return 1;
	case '2': return 2;
	case '3': return 3;
	case '4': return 4;
	case '5': return 5;
	case '6': return 6;
	case '7': return 7;
	case '8': return 8;
	case '9': return 9;
	default: return 0;
	}
}
using namespace std;
typedef long long ll;
//定義場所//
int i, j, k, l, m, n;
int N, Q;
vector <int> Ans;
////////////

int main()
{
	int N;
	cin >> N;
	for (k = 0; k < N; k++) {
		vector<vector<int> >dp(1001, vector<int>(1001, 0));
		int ans = 0;
		string s1, s2;
		cin >> s1 >> s2;
		s1 = ' ' + s1;
		s2 = ' ' + s2;
		for (i = 0; i < s1.size(); i++) { dp[i][0] = 0; }
		for (i = 1; i < s2.size(); i++) { dp[0][i] = 0; }
		for (i = 1; i < s1.size(); i++) {
			for (j = 1; j < s2.size(); 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]);
				}
				ans = max(ans, dp[i][j]);
			}
		}
		Ans.push_back(ans);
	}
	for (i = 0; i < Ans.size(); i++) {
		cout << Ans[i] << endl;
	}
}

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

int lcs(string X, string Y) {
  int cs[1001][1001];
  int m = X.size();
  int n = Y.size();
  int answer = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  for (int i = 1; i <= m; i++) cs[i][0] = 0;
  for (int j = 1; j <= n; j++) cs[0][j] = 0;

  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; j++) {
      if (X[i] == Y[j]) {
        cs[i][j] = cs[i - 1][j - 1] + 1;
      } else {
        cs[i][j] = max(cs[i - 1][j], cs[i][j - 1]);
      }
      answer = max(answer, cs[i][j]);
    }
  }

  return answer;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n;
  cin >> n;

  string X, Y;

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

  return 0;
}