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] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// 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;

int main() {
	int q;
	string strX, strY;

	cin >> q;
	for (int n = 0; n < q; n++) {
		cin >> strX;
        cin >> strY;
		char X[strX.length() + 1];
		for (int x = 0; x < strX.length(); x++) {//文字列を配列に入れる
			X[x + 1] = strX[x];
		}

        char Y[strY.length() + 1];
		for (int y = 0; y < strY.length(); y++) {//文字列を配列に入れる
			Y[y + 1] = strY[y];
		}

        int c[strX.length()+1][strY.length()];
        int maxLen = 0;

		for (int i = 0; i<=strX.length(); i++){
            for(int j = 0; j<=strY.length(); j++){
                if(i == 0 || j == 0){
                    c[i][j] = 0;
                }
                else 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]);
                }

                if(c[i][j] > maxLen){
                    maxLen = c[i][j];
                }
            }
        }
        cout << maxLen << endl;
	}

    return 0;
}

C++: #include <bits/stdc++.h>
#define debug(x) cerr << #x << ": " << x << '\n';
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = (int)1e9;
const int MOD = (int)1e9 + 7;

int dp[1001][1001];

int main(void){
	int q;
	cin >> q;

	vector<int> res;
	for(int i = 0; i < q; i++){
		string s, t;
		cin >> s >> t;

		fill(dp[0], dp[1000] + 1000, 0);
		for(int j = 0; j < s.size(); j++){
			for(int k = 0; k < t.size(); k++){
				if(s[j] == t[k]) dp[j+1][k+1] = dp[j][k] + 1;
				else dp[j+1][k+1] = max(dp[j+1][k], dp[j][k+1]);
			}
		}

		res.push_back(dp[s.size()][t.size()]);
	}

	for(int i = 0; i < q; i++) cout << res[i] << '\n';

	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 <iostream>
#include <cmath>
#include <vector>
#include <string>
#include <algorithm>

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    int n;
    std::cin >> n;
    std::string s1, s2;
    for (int q=0; q<n; q++) {
        std::cin >> s1 >> s2;
        int m1 = s1.size()+1;
        int m2 = s2.size()+1;
        int* dp = (int*)malloc(m1*m2*sizeof(int));
        for (int i=0; i<m1; i++) {
            dp[i*m2]=0;
        }
        for (int i=0; i<m2; i++) {
            dp[i]=0;
        }
        for (int i=1; i<m1; i++) {
            int leftmax=0;
            for (int j=1; j<m2; j++) {
                dp[i*m2+j] = leftmax;
                if (s1[i-1] == s2[j-1]) {
                    dp[i*m2+j]+=1;
                }
                if (dp[(i-1)*m2+j] > leftmax) {
                    leftmax = dp[(i-1)*m2+j];
                }
                if (dp[i*m2+j] < dp[(i-1)*m2+j]) {
                    dp[i*m2+j] = dp[(i-1)*m2+j];
                }
            }
        }
        int max=0;
        for (int i=0; i<m2; i++) {
            if (dp[(m1-1)*m2+i] > max) {
                max = dp[(m1-1)*m2+i];
            }
        }
        std::cout << max << "\n";
        free(dp);
    }

    return 0;
}

C++: #include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
using namespace std;
const int maxn = 1005;

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();
		cout << lcs() << endl;
	}
	return 0;
}

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

using std::cin;
using std::cout;
using std::cerr;
using std::endl;

// 最長共通部分列 ... len(s) == m, len(t) == n とすると, O(mn)
int lcs(std::string s, std::string t) {
  std::vector<std::vector<int> > dp(s.size() + 1, std::vector<int>(t.size() + 1, 0));

  for (int i = 0; i < s.size(); ++i) {
    for (int j = 0; j < t.size(); ++j) {
      if (s[i] == t[j]) {
        dp[i][j] = (i == 0 ? (j == 0 ? 1 : 0) : ;
      }
      else if (i >= 0 && j >= 0 && dp[i - 1][j] >= dp[j][i - 1]) {
        dp[i][j] = dp[i - 1][j];
      }
      else if (i >= 0 && j >= 0) {
        dp[i][j] = dp[i][j - 1];
      }
    }
  }

  return dp[s.size()][t.size()];
}

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

  return 0;
}