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 <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <queue>

#define INPUT_FROM_FILE (0) 
#if INPUT_FROM_FILE
#include <fstream>
#endif

int main(int argc, char **argv){
	std::string X, Y;
	int q;

#if INPUT_FROM_FILE
	std::ifstream ifs("test.txt");
	//FILE *fp = fopen("test.txt", "r");
#endif


#if INPUT_FROM_FILE
	std::getline(ifs, X);
#else
	std::getline(std::cin, X);
#endif
	q = std::stoi(X);

	for(int i = 0; i < q; i++){
		std::vector<std::vector<int> > dp;
#if INPUT_FROM_FILE
		std::getline(ifs, X);
		std::getline(ifs, Y);
#else
		std::getline(std::cin, X);
		std::getline(std::cin, Y);
#endif
		dp.resize(X.size() + 1);
		for(int i = 0; i < dp.size(); i++){
			dp[i].resize(Y.size() + 1, 0);
		}

		for(int i = 0; i < X.size(); i++){
			for(int j = 0; j < Y.size(); j++){
				if(X[i] == Y[j]){
					dp[i + 1][j + 1] = dp[i][j] + 1;
				}
				else{
					dp[i + 1][j + 1] = std::max(dp[i + 1][j], dp[i][j + 1]);
				}
			}
		}
		std::cout << dp[X.size()][Y.size()] << std::endl;
	}
	return 0;
}

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

int q;
string X,Y;
int L[1001][1001];

int max(int i,int j) {return i > j ? i : j;}

int getL(int i,int j) {
	if(L[i][j] != -1) return L[i][j];

	int res;

	if(i == 0 || j == 0) res = 0;
	else if(X[i - 1] == Y[j - 1]) res = 1 + getL(i - 1,j - 1);
	else res = max(getL(i,j - 1),getL(i - 1,j));

	L[i][j] = res;
	return res;
}

int main() {

	cin >> q;
	for(int i = 0;i < q;i++) {
		cin >> X >> Y;
		for(int j = 0;j <= X.size();j++) {
			for(int k = 0;k <= Y.size();k++) L[j][k] = -1;
		}
		cout << getL(X.size(),Y.size()) << endl;
	}
}

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <functional>

using namespace std;
using ll = long long int;
#define rep(i,n) for(int i = 0; i < n; i++)
#define FOR(i, a, b)  for(int i = (a); i < (b) ; i++)
#define pb push_back
#define SORT(v,n) sort(v, v+n)
#define ALL(x) (x).begin(),(x).end()
#define debug(x) cerr << #x << ": " << x << '\n'
#define elif else if
#define itn ll
#define int ll
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
///                →,↑,←,↓,↗,↖,↙,↘
int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };


static const int N = 1000;

int lcs(string X, string Y) {
	int c[N + 1][N + 1];
	int maxl = 0;
	int i, j;
	int m = X.size();
	int n = Y.size();
	X = ' ' + X;
	Y = ' ' + Y;
	FOR(i, 1, m+1) {
		c[i][0] = 0;
	}
	FOR(i, 1, n+1) {
		c[0][i] = 0;
	}
	for (int i = 1; i <= m; i++) {
		for (int j = 1; j <= n; j++) {
			if (X[i] == X[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(c[i][j], maxl);
		}
	}
	return maxl;
}

signed main() {
	ios::sync_with_stdio(false);
	int n;
	string s1, s2;
	cin >> n;
	int i;
	rep(i, n) {
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << "\n";
	}
	return 0;
}

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 = 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 x, y;
  int n;
  cin >> n;
  for(int i = 0 ; i < n ; i++){
    cin >> x >> y;
    cout << lcs(x,y) << endl;
  }
return 0;

}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;++i)
#define rep1(i,n) for(int i=1;i<=n;++i)
#define eachdo(e,array) for(const auto& e : array)
#define lower_index(v,a) (int)distance(v.begin(), lower_bound((v).begin(),(v).end(),a))
template<class T> bool chmin(T &a, T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T &a, T b){if(a<b){a=b;return true;}return false;}
typedef long long ll;
const int inf = 1<<28;
const ll INF = 1LL<<57;
const ll MOD = 1e9+7;

int main(){ 
    ll N; cin >> N;
    rep(_,N){
        string x,y;cin >> x >> y;
        ll X = x.size();
        ll Y = y.size();
        vector<vector<ll>> dp(X+1,vector<ll>(Y+1,0));
        rep(i,X)rep(j,Y){
            if (x[i]==y[j]) chmax(dp[i+1][j+1],dp[i][j]+1);
            else chmax(dp[i+1][j+1],max(dp[i+1][j],dp[i][j+1]));
        }
        cout << dp[X][Y] << endl;
    }

}