Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

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 i = 1; i <= n; i++) c[0][i] = 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 n;
	string s1, s2;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << endl;
	}
    return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
static const int N = 1001;

int lcs(string X, string Y){
    int c[N][N];
    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 = 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(){
    int q;
    cin >> q;
    while(q--){
        string a,b; cin >> a >> b;
        cout << lcs(a,b) << endl;
    }
}

C++: #include <iostream>

using namespace std;

typedef long long signed int ll;

constexpr ll NIL = -20000000000;

string s[2];
int dp[1001][1001];

int lcs(int x,int y) {
    if(x < 0 || y < 0) return 0;
    if(x >= s[0].size() || y >= s[1].size()) return 0;
    if(dp[x][y] == -1) {
        dp[x][y] = max(lcs(x+1,y),dp[x][y]);
        dp[x][y] = max(lcs(x,y+1),dp[x][y]);
        if(s[0][x] == s[1][y]) dp[x][y] = max(lcs(x+1,y+1) + 1,dp[x][y]);
    }
    return dp[x][y];
}

int main() {
    int n;
    cin >> n;
    for(int i = 0;i < n;i++) {
        cin >> s[0] >> s[1];
        int res = -1;
        for(int j = 0;j < 1001 * 1001;j++)(reinterpret_cast<int*>(dp))[j] = -1;
        for(int j = 0;j < 1001 * 1001;j++)res = max(res,(reinterpret_cast<int*>(dp))[j]);
        cout << lcs(0,0) << endl;
    }
}

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

#define MAX 1000

int DP[MAX][MAX];

int main(){
  int n;
  
  std::cin >> n;
  
  for(int t = 0; t < n; t++){
    std::string str1, str2;

    std::cin >> str1;
    std::cin >> str2;
    
    const int one_len = str1.length();
    const int two_len = str2.length();
    
    for(int i = 0; i < one_len; i++){
      for(int j = 0; j < two_len; j++){
	DP[i][j] = 0;
      }
    }

    for(int i = 0; i < one_len; i++){
      for(int j = 0; j < two_len; j++){
	if(i == 0 && j == 0){
	  DP[i][j] = str1[i] == str2[j] ? 1 : 0;
	}else if(i == 0){	
	  DP[i][j] = std::max(DP[i][j-1], str1[i] == str2[j] ? 1 : 0);
	}else if(j == 0){
	  DP[i][j] = std::max(DP[i-1][j], str1[i] == str2[j] ? 1 : 0);
	}else{
	  DP[i][j] = std::max(DP[i-1][j-1] + (str1[i] == str2[j] ? 1 : 0), std::max(DP[i-1][j], DP[i][j-1]));
	}
      }
    }
    
    std::cout << DP[one_len - 1][two_len - 1] << std::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; // X[0]に空白を挿入
    Y = ' ' + Y;
    for (int i=0; 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][j-1], C[i-1][j]);
            }
            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>
using namespace std;
int main(){
    int n;
    cin >> n;
    for(int q=0;q<n;q++){
        string x,y;
        cin >>x >> y;
        int dp[1002][1002];
        memset(dp,-1, sizeof(dp));
        dp[0][0] = 0;
        for(int i=0;i<x.size()+1;i++){
            for(int j=0;j<y.size()+1;j++){
                if (i < x.size() && j < y.size() && x[i] == y[j]){
                dp[i+1][j+1] = max(dp[i+1][j+1], dp[i][j] + 1);
                }
                dp[i][j+1] = max(dp[i][j+1],dp[i][j]);
                dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
            }
        }
        cout << dp[x.size()][y.size()] << endl;
    }
}