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 <bits/stdc++.h>
using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)
#define REPR(i, n) for(int i = n; i >= 0; i--)
#define FOR(i, m, n) for(int i = m; i < n; i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define INF 1e9
typedef long long ll;


int main() {
    int q;
    cin >> q;
    REP(k,q){
        string X,Y;
        cin >> X;
        cin >> Y;
        int m,n;
        m = X.length();
        n = Y.length();

        vector<vector<int>> dp(m+1, vector<int>(n+1,0));

        REP(i,m){
            REP(j,n){
                if(X[i] == Y[j]){
                    dp[i+1][j+1] = max({dp[i+1][j+1], dp[i][j]+1});
                }
                dp[i+1][j+1] = max({dp[i+1][j+1], dp[i+1][j], dp[i][j+1]});
            }
        }
        cout << dp[m][n] << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<string>
int main()
{
  int n;
  int an[1000];
  int l=0;
  std::cin>>n;
  std::string x;
  std::string y;
  int ans[1001][1001];
  int j,k;
  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<=1000;j++){
      for(int k=0;k<=1000;k++){
	ans[j][k]=0;
      }
    }
    for(int j=1;j<=x.size();j++){
      for(int k=1;k<=y.size();k++){
	if(x[j]==y[k]){
	  ans[j][k]=ans[j-1][k-1]+1;
	}else{
	  if(ans[j][k-1]>ans[j-1][k]){
	    ans[j][k]=ans[j][k-1];
	  }else{
	    ans[j][k]=ans[j-1][k];
	  }
	}
      }
    }
    std::cout<<ans[x.size()-1][y.size()-1]<<'\n';  
  }
  return 0;
}

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

static int lc[1000][1000];
static std::string X, Y;

int count(int idx_x, int idx_y) {
    if (lc[idx_x][idx_y] != -1) {
        return lc[idx_x][idx_y];
    }

    int maximum = 0;
    
    if (X[idx_x] == Y[idx_y]) {
        if (idx_x > 0 && idx_y > 0) {
            maximum = std::max(maximum, count(idx_x - 1, idx_y - 1));
        }
        lc[idx_x][idx_y] = maximum + 1;
    } else {
        if (idx_x > 0) {
            maximum = std::max(maximum, count(idx_x - 1, idx_y));
        }
        if (idx_y > 0) {
            maximum = std::max(maximum, count(idx_x, idx_y - 1));
        }
        lc[idx_x][idx_y] = maximum;
    }
    return lc[idx_x][idx_y];
}

int LongestCommon() {
    for (int i = 0; i < X.length(); i++) {
        for (int j = 0; j < Y.length(); j++) {
            lc[i][j] = -1;
        }
    }
    return count(X.length() - 1, Y.length() - 1);
}

int main() {
    int q;
    std::cin >> q;
    for (int i = 0; i < q; i++) {
        std::cin >> X >> Y;
        std::cout << LongestCommon() << std::endl;
    }
}

C++: #include<iostream>
#include<map>
#include<vector>
#include<algorithm>
#include<cmath>
#include<climits>
#include<ctime>
#include<cstring>
#include<numeric>

#define ALL(v) (v).begin(),(v).end()
#define REP(i,p,n) for(int i=p;i<(int)(n);++i)
#define rep(i,n) REP(i,0,n)
#define dump(a) (cerr << #a << "=" << (a) << endl)
#define DUMP(list) cout << "{ "; for(auto nth : list){ cout << nth << " "; } cout << "}" << endl;

using namespace std;


int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  int N, al, bl;
  string k, l;
  int ans[1001][1001];
  cin >> N;

  rep(i, N){
    cin >> k;
    cin >> l;

    al = k.length();
    bl = l.length();


    rep(j, al+1){
      rep(s, bl+1){
        ans[j][s] = 0;
      }
    }

    rep(j, al){
      rep(s, bl){
        if(k[j] == l[s]){
          ans[j+1][s+1] = max(ans[j+1][s], max(ans[j][s+1], ans[j][s] + 1));
        } else{
          ans[j+1][s+1] = max(ans[j+1][s], ans[j][s+1]);
        }
      }
    }

    cout << ans[al][bl] << "\n";



  }
}

C++: #include<bits/stdc++.h>
using namespace std;

int dp[1001][1001];
int main() {
	int b;
	scanf("%d", &b);
	char e[1001];
	char f[1001];
	for (int c = 0; c < b; c++) {
		scanf("%s%s", e, f);
		for (int g = 0; g <= strlen(e); g++) {
			for (int h = 0; h <= strlen(f); h++) {
				dp[g][h] = 0;
			}
		}
		for (int g = 1; g <= strlen(e); g++) {
			for (int h = 1; h <= strlen(f); h++) {
				if (e[g] == f[h]) {
					dp[g][h] = dp[g - 1][h - 1] + 1;
				}
				else {
					dp[g][h] = max(dp[g][h - 1], dp[g - 1][h]);
				}
			}
		}
		printf("%d\n", dp[strlen(e)][strlen(f)]);
	}
}