Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

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;
}



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<iostream>
#include<cstdio>
#include<string>
using namespace std;

#define MAX_N 1000
#define MAX_M 1000

//入力
int n;
string s, t;
//char s[MAX_N], t[MAX_M];

int dp[MAX_N + 1][MAX_M + 1]; //DPテーブル

void solve(){
	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];
					dp[i + 1][j + 1] = dp[i][j] + 1;
				} else {
					dp[i + 1][j + 1] = max(dp[i][j], dp[i + 1][j]);
				}
			}
		}
		printf("%d\n", dp[s.size()][t.size()]);
}

int main(){
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> s >> t;
		solve();
	}
}

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

int dp[1002][1002] = { 0 };

int main() {
	int q;
	cin >> q;
	for (int i = 0; i < q; ++i) {
		string x, y;
		int cnt = 0;
		cin >> x >> y;
		memset(dp, 0, sizeof(dp));

		for (int j = 1; j <= x.size(); ++j) {
			for (int j2 = 1; j2 <= y.size(); ++j2) {
				if (x[j - 1] == y[j2 - 1]) {
					dp[j][j2] = max(dp[j][j2 - 1], dp[j - 1][j2 - 1] + 1);
				}
				else {
					dp[j][j2] = max(dp[j][j2 - 1], dp[j - 1][j2 - 1]);
				}
			}
		}
		cout << dp[x.size()][y.size()] << endl;
	}

	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int q;
char x[1010],y[1010];
int dp[1010][1010];
int lcs(char * str1,char* str2){
	for(int i=0;i<=strlen(str1);i++){
		dp[i][0]=0;
	}
	for(int j=0;j<=strlen(str2);j++){
		dp[0][j]=0;
	}
	int temp;
	for(int i=1;i<=strlen(str1);i++){
		for(int j=1;j<=strlen(str2);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]);
			}
		}
	}
	return dp[strlen(str1)][strlen(str2)];
}
int main(){
	cin>>q;
	for(int time=0;time<q;time++){
		cin>>x>>y;
		int re=lcs(x,y);
		cout<<re<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <string>
int main(){
    int q;
    std::cin >> q;
    for(int p = 0; p < q; p++){
        std::string X, Y;
        std::cin >> X >> Y;
        int dp[X.size() + 1][Y.size() + 1];
        dp[0][0] = 0;
        for(int i = 0; i < X.size() + 1; i++){
            for(int j = 0; j < Y.size() + 1; j++) dp[i][j] = 0;
        }
        for(int i = 1; i < X.size() + 1; i++){
            for(int j = 1; j < Y.size() + 1; j++){
                if(X[i - 1] == Y[j - 1]) dp[i][j] = std::max(dp[i - 1][j - 1] + 1, std::max(dp[i - 1][j], dp[i][j - 1]));
                else dp[i][j] = std::max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
        std::cout<< dp[X.size()][Y.size()] << std::endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, m, n) for (int i = m; i < n; ++i)
template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; }

int solve() {
  string X, Y;
  cin >> X >> Y;
  int N = X.size();
  int M = Y.size();
  int dp[1010][1010] = {};
  rep(i, 0, N) rep(j, 0, M) {
    if(X[i] == Y[j]) {
      chmax(dp[i + 1][j + 1], dp[i][j] + 1);
    } else {
      chmax(dp[i + 1][j + 1], dp[i + 1][j]);
      chmax(dp[i + 1][j + 1], dp[i][j + 1]);
    }
  }
  cout << dp[N][M] << "\n";
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int q; cin >> q;
  rep(i, 0, q) solve();
  return 0;
}

C++: import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        String X = null, Y = null;
        int[][] dp = new int[1001][1001];

        int q = sc.nextInt();

        for (int i = 0; i < q; ++i) {
            X = sc.next();
            Y = sc.next();
            for (int x = 0; x < X.length(); ++x) {
                for (int y = 0; y < Y.length(); ++y) {
                    if (X.charAt(x) == Y.charAt(y)) {
                        dp[x + 1][y + 1] = dp[x][y] + 1;
                    }
                    else {
                        if (dp[x + 1][y] > dp[x][y + 1]) {
                            dp[x + 1][y + 1] = dp[x + 1][y];
                        }
                        else {
                            dp[x + 1][y + 1] = dp[x][y + 1];
                        }
                    }
                }
            }
            System.out.printf("%d\n", dp[X.length()][Y.length()]);
        }
    }
}

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

using namespace std;

string s, t;

int main() {
	int n;
	cin >> n;
	while (n--) {
		//dp[i][j] := s???i??????????????§???t???j??????????????§?????£?????¨??????LCS
		vector<vector<int>> dp(2000, vector<int>(2000));
		cin >> s >> t;
		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] = dp[i][j] + 1;
				else dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
			}
		}
		cout << dp[s.size()][t.size()] << 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 = 0; 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;
}