Go: package main

/*
最長共通部分列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func larger(l, r int) int {
	if l > r {
		return l
	}
	return r
}

var memo [1001][1001]int

func countLCS(x, y string) int {
	x = " " + x
	y = " " + y
	max := 0
	for xi := 1; xi < len(x); xi++ {
		for yi := 1; yi < len(y); yi++ {
			if x[xi] == y[yi] {
				memo[xi][yi] = memo[xi-1][yi-1] + 1
			} else {
				memo[xi][yi] = larger(memo[xi-1][yi], memo[xi][yi-1])
			}
			max = larger(max, memo[xi][yi])
		}
	}
	return max
}

func main() {
	scanner := makeScanner(1024)
	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		x := eGetLine(scanner)
		y := eGetLine(scanner)
		fmt.Println(countLCS(x, y))
	}
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include <iostream> // cout, endl, cin
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <iomanip>
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
#include <math.h>
#include <cmath>
#include <stdlib.h>
#include <stdio.h>
using namespace std;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
const int INF = 1001001000;
const int MOD = 1000000007;

long long gcd(long long a, long long b) {
    if (b == 0) return a;
    else return gcd(b, a % b);
}
long long lcm(long long a, long long b) {
    return a * b / gcd(a, b);
}

using Graph = vector<vector<int>>;
//再帰とかグラフを使うときは予めNの最大値のグローバル配列を取っておく
int N;
vector<int> E[200001];
bool shipment[15][15];
vector<bool> seen;
typedef pair<int, int> P;
int D[101];
//頂点状態を表すcolor[]において、0は未訪問、1は訪問中、2は完了を表す。
int color[101];
int find_time = 0;
int dp[1001][1001];

void solve_LCS(string X,string Y) {
    int S = X.size();
    int T = Y.size();
    for (int i = 0; i < S; i++) {
        for (int j = 0; j < T; j++) {
            //同じ文字だったら、max(今まで+1,今までの最大)をする
            if (X[i] == Y[j]) dp[i + 1][j + 1] = max({ dp[i][j] + 1,dp[i + 1][j],dp[i][j + 1] });
            else dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
        }
    }

    cout << dp[S][T] << endl;
}

int main() {
    int Q; cin >> Q;
    vector<string> Xs(Q);
    vector<string> Ys(Q);
    for (int i = 0; i < Q; i++) {
        cin >> Xs.at(i) >> Ys.at(i);
    }
    for (int i = 0; i < Q; i++) {
        solve_LCS(Xs.at(i),Ys.at(i));
    }
}

C++: #include<iostream>
#include<stdio.h>
#include<string>
#include<algorithm>
#define MAX 10001

using namespace std;

int c[MAX][MAX]; 
int n, m;
int maxlengh;

int lcs(string A, string B) {
	maxlengh = 0;
	A = ' ' + A;
	B = ' ' + B;
	n = A.size();
	m = B.size();

	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			if (i == 0 || j == 0) {
				c[i][j] = 0;
			}else if(A[i] == B[j]) {
				c[i][j] = c[i - 1][j - 1] + 1;
			}else{
				c[i][j] = max(c[i][j - 1], c[i - 1][j]);
			}maxlengh = max(maxlengh, c[i][j]);
		}
	}
	return maxlengh;
}

int main() {
	int q;
	cin >> q;
	string a, b;
	
	for (int i = 0; i < q; i++) {
		cin >> a >> b;
		cout << lcs(a, b) << endl;
	}
	return 0;
}

C++: //#define		FILE_INPUT_DEFINE
#ifdef		FILE_INPUT_DEFINE
#include	<fstream>
#endif		// FILE_INPUT_DEFINE

#include	<iostream>
#include	<string>
#include	<algorithm>

using namespace std;

#define			MAX		1000
#define			ind(x)		((x) - 1)

int C[MAX][MAX];

int LCS(string &X, string &Y)
{
	int			Xlen = X.length();
	int			Ylen = Y.length();

	for (int i = 0; i <= Xlen; ++i)
	{
		C[i][0] = 0;
	}

	for (int i = 0; i <= Ylen; ++i)
	{
		C[0][i] = 0;
	}

	for (int i = 1; i <= Xlen; ++i)
	{
		for (int j = 1; j <= Ylen; ++j)
		{
			if (X[ind(i)] == Y[ind(j)])
			{
				C[i][j] = C[i - 1][j - 1] + 1;
			}
			else
			{
				C[i][j] = max(C[i - 1][j], C[i][j - 1]);
			}
		}
	}

	return (C[Xlen][Ylen]);
}

int main()
{
#ifdef		FILE_INPUT_DEFINE
	// input from txt
	std::ifstream in(R"(C:\Temp\input.txt)");
	std::cin.rdbuf(in.rdbuf());
#endif		// FILE_INPUT_DEFINE

	string	X, Y;
	int		n;

	cin >> n;
	cin.clear();
	cin.ignore();

	for (int i = 0; i < n; ++i)
	{
		getline(cin, X);
		getline(cin, Y);

		cout << LCS(X, Y) << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <string>
#include <queue>
#include <stack>
#include <functional>
#include <complex>
#include <cmath>
#include <ccomplex>
using namespace std;

void solve() {
	string x, y;
	cin >> x >> y;
	int xlen = x.length();
	int ylen = y.length();
	int dp[155][155];
	dp[0][0] = 0;

	for (int i = 0; i <= xlen; i++) {
		for (int j = 0; j <= ylen; j++) {
			if (i == 0 || j == 0) {
				dp[i + 1][j + 1] = 0;
			}
			else if (x[i - 1] == y[j - 1]) {
				dp[i + 1][j + 1] = dp[i][j] + 1;
			}
			else {
				dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j]);
			}
		}
	}
	cout << dp[xlen + 1][ylen + 1] << endl;
}
int main() {
	int q;
	cin >> q;
	for (int i = 0; i < q; i++)solve();
}