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 <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) for(int i=0;i < (n);i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define SCANF(i) int i;scanf("%d",&i)
typedef long long ll;
using namespace std;
using P = pair<int,int>;
const long long INF = 1LL << 60;
const int IINF=100000000;
const int MOD = (int)1e9 + 7;
//約数列挙
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    //sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}
vector<int> dx={1,0,-1,0};vector<int> dy={0,-1,0,1};

signed main () {
    int n;cin >> n;
    REP(i,n){
        string s,t;cin >> s >> t;
        int slen=s.length();int tlen=t.length();
        vector<vector<int>> lcm(slen+1,vector<int>(tlen+1,0));
        REP(i,s.length())REP(j,t.length()){
            if(s[i]==t[j]){
                lcm[i+1][j+1]=max({lcm[i][j+1],lcm[i+1][j],lcm[i][j]+1});
            }
            lcm[i+1][j+1]=max({lcm[i+1][j+1],lcm[i+1][j],lcm[i][j+1]});
        }
        cout << lcm[slen][tlen] << endl;
    }

}

C++: #include <iostream>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>

#include <cstdio>

using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, s, n) for (int i = (s); i <= (n); i++)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rrep1(i, s, n) for (int i = (s); i >= (n); i--)
#define print_array(ary, size) cout << ary[0]; rep1(i, 1, size - 1) cout << ' ' << ary[i]; cout << endl;
typedef long long ll;
typedef unsigned long long ull;


int dp[1000][1000];

int getLCS(string* s1, string* s2, int s1i, int s2i)
{
	int ret;
	int cand1, cand2;

	if (s1i < 0 || s2i < 0) {
		return 0;
	}
	else if (dp[s1i][s2i] != -1) ret = dp[s1i][s2i];
	else if ((*s1)[s1i] == (*s2)[s2i]) {
		ret = getLCS(s1, s2, s1i - 1, s2i - 1) + 1;
	}
	else {
		cand1 = getLCS(s1, s2, s1i, s2i - 1);
		cand2 = getLCS(s1, s2, s1i - 1, s2i);
		ret = max(cand1, cand2);
	}
	dp[s1i][s2i] = ret;

	return ret;
}

int main()
{
	int q;
	int ans;
	string s1, s2;

	cin >> q;
	rep(i, q) {
		rep(j, 1000) {
			rep(k, 1000) dp[j][k] = -1;
		}
		cin >> s1 >> s2;
		ans = getLCS(&s1, &s2, s1.length() - 1, s2.length() - 1);
		cout << ans << endl;
	}

	return 0;
}