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 <cmath>
#include <set>
#include <string>
#include <algorithm>
#include <vector>
#include <bitset>
#include <iomanip>
#include <map>

using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;
using std::bitset;

#define rep(i,n)    for(int i=0; i<(int)n; i++)
#define reps(i,s,e) for(int i=s; i<(int)e; i++)
typedef long double ld;
typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef std::pair<int, int> pii;
typedef std::pair<ll, ll> pll;

template<class T>
using Graph = vector<vector<T>>;

void printFixedDouble(double d, int fix) {
    cout << std::fixed;
    cout << std::setprecision(fix) << d << endl;
}

int main() {
    int datanum;
    cin >> datanum;
    rep(d, datanum) {
        string a, b;
        cin >> a >> b;

        int aLen = a.length();
        int bLen = b.length();

        int dp[aLen + 1][bLen + 1];
        rep(i, aLen + 1) {
            dp[i][0] = 0;
        }
        rep(i, bLen + 1) {
            dp[0][i] = 0;
        }

        rep(i, aLen) {
            rep(j, bLen) {
                if (a[i] == b[j]) {
                    dp[i+1][j+1] = std::max(std::max(dp[i+1][j], dp[i][j+1]), dp[i][j] + 1);
                } else {
                    dp[i+1][j+1] = std::max(dp[i+1][j], dp[i][j+1]);
                }
            }
        }

        cout << dp[aLen][bLen] << endl;
    }
}

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

using namespace std;
const int L = 1001;
const int INF = -1001001001;

int main()
{
    string s, t;
    int dp[L][L];
    int q;
    cin >> q;
    for(int i=0;i<q;++i)
    {
        cin >> s;
        cin >> t;
        for(int j=0;j<s.size()+1;++j) dp[j][0] = 0;
        for(int j=0;j<t.size()+1;++j) dp[0][j] = 0;
        for(int j=1;j<s.size()+1;++j)
        {
            for(int k=1;k<t.size()+1;++k)
            {
                if(s[j-1] == t[k-1])
                {
                    dp[j][k] = max(max(dp[j][k-1], dp[j-1][k-1] + 1), dp[j-1][k]);
                }
                else
                {
                    dp[j][k] = max(dp[j][k-1], dp[j-1][k]);
                }
            }
        }
        cout << dp[s.size()][t.size()] << endl;
    }
}

C++: #include <math.h>
#include <stdlib.h>
#include <algorithm>
#include <array>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

#define rep(i, n) for (int i = 0; i < (n); i++)
#define loop(i, a, n) for (int i = a; i < (n); i++)
#define all(in) in.begin(), in.end()
const int INF = 1e9;
const int MOD = 1e9 + 7;
#define MAX_q 150
#define MAX_L 1000
string X, Y;
int dp[MAX_L + 1][MAX_L + 1];
void DP() {
    rep(i, X.size()) {
        rep(k, Y.size()) { dp[i][k] = 0; }
    }
    rep(i, X.size()) {
        rep(k, Y.size()) {
            if (X[i] == Y[k]) {
                dp[i + 1][k + 1] = dp[i][k] + 1;
            } else {
                dp[i + 1][k + 1] = max(dp[i][k + 1], dp[i + 1][k]);
            }
        }
    }
}
int main() {
    int q;
    cin >> q;
    rep(j, q) {
        cin >> X >> Y;
        DP();
        cout << dp[X.size()][Y.size()] << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int dp[1001][1001];




	
int main (){
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	//input
	int n;
	cin >> n;
	vector<string> S(n);
	vector<string> T(n);
	for(int i=0;i<n;i++)cin >> S[i] >> T[i];


	//alorithm
	for(int i=0;i<n;i++){
		string s,t;
		s=S[i];
		t=T[i];
		memset(dp,0,sizeof(dp));
		for(int i=1;i<=s.size();i++){
			for(int j=1;j<=t.size();j++){
				if(s[i-1]==t[j-1]){dp[i][j]=dp[i-1][j-1]+1;continue;}
				dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
			}
		}
		cout << dp[s.size()][t.size()] << endl;
	}
}