Go: package main

import (
	"bufio"
	"os"
	"fmt"
	"strconv"
)

const max int = 1000 + 1
var A [][]int

func lcs(x, y string) int {
	x = " " + x
	y = " " + y
	for i:=0;i<len(x); i++ {
		for j:=0;j<len(y); j++ {
			A[i][j] = 0
		}
	}
	for i:=1; i<len(x); i++ {
		for j:=1; j<len(y); j++ {
			if x[i] == y[j] {
				A[i][j] = A[i-1][j-1] + 1
			} else if A[i-1][j] > A[i][j-1] {
				A[i][j] = A[i-1][j]
			} else {
				A[i][j] = A[i][j-1]
			}
		}
	}
	return A[len(x)-1][len(y)-1]
}

func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num 
}

func nextStr(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}


func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	A = make([][]int, max)
	for i := range A {
		A[i] = make([]int, max)
	}
	n := nextInt(scanner)
	for i:=0; i<n; i++ {
		x := nextStr(scanner)
		y := nextStr(scanner)
		fmt.Printf("%d\n", lcs(x, y))
	}
}

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

int main()
{
	int n;
	string a, b;

	while (n--)
	{
		int memo1[1005] = {};
		int memo2[1005] = {};
		cin >> a >> b;

		for (int i = 1; i <= a.size(); i++)
		{
			memo2[0] = 0;
			for (int j = 1; j <= b.size(); j++)
			{
				if (a[i] == b[j])
					memo2[j] = max({ memo2[j - 1], memo1[j], memo1[j - 1] + 1 });
				else
					memo2[j] = max(memo2[j - 1], memo1[j]);
			}
			swap(memo1, memo2);
		}

		cout << memo1[b.size()] << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <climits>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <sstream>
#include <numeric>
// #include <boost/multiprecision/cpp_dec_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>

///////////////////////////////////////////////////////////////
// namespace
///////////////////////////////////////////////////////////////
using namespace std;
// namespace mp = boost::multiprecision;

///////////////////////////////////////////////////////////////
// types
///////////////////////////////////////////////////////////////
using pii = pair<int, int>;
using ll = long long int;
using ld = long double;
// using mpi = mp::cpp_int;
// using mpf = mp::number<mp::cpp_dec_float<1024>>;

///////////////////////////////////////////////////////////////
// mod https://qiita.com/drken/items/3b4fdf0a78e7a138cd9a
///////////////////////////////////////////////////////////////
// ll MOD = 1000000007;
// ll mod(long long val) {
//     long long res = val % MOD;
//     if (res < 0) res += MOD;
//     return res;
// }
// ll modinv(ll a) {
//     ll b = MOD, u = 1, v = 0;
//     while (b) {
//         ll t = a / b;
//         a -= t * b; swap(a, b);
//         u -= t * v; swap(u, v);
//     }
//     u %= MOD;
//     if (u < 0) u += MOD;
//     return u;
// }

vector<vector<int>> dp;

int lcs(const string &x, const string &y, int i, int j) {
    if (i >= x.size() || j >= y.size()) return 0;
    if (dp[i][j] >= 0) return dp[i][j];
    int ret = 0;
    ret = max(ret, lcs(x, y, i + 1, j));
    ret = max(ret, lcs(x, y, i, j + 1));
    if (x[i] == y[j]) ret = max(ret, lcs(x, y, i + 1, j + 1) + 1);
    return dp[i][j] = ret;
}

int lcs(const string &x, const string &y) {
    for (int i = x.size() - 1; i >= 0; --i) {
        for (int j = y.size() - 1; j >= 0; --j) {
            dp[i][j] = max(dp[i][j], dp[i + 1][j]);
            dp[i][j] = max(dp[i][j], dp[i][j + 1]);
            if (x[i] == y[j]) dp[i][j] = max(dp[i][j], dp[i + 1][j + 1] + 1);
        }
    }
    return dp[0][0];
    // return lcs(x, y, 0, 0);
}

int main() {
    int n;
    string x, y;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> x >> y;
        dp = vector<vector<int>>(x.size() + 5, vector<int>(y.size() + 5, 0));
        cout << lcs(x, y) << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
using namespace std;
#define MAX 1001

int lcs(string X, string Y){
  int c[MAX][MAX]; 
  int m = X.length();
  int n = Y.length();
  for(int i=0; i<m; i++){
    c[i][0] = 0;
  }
  for(int i=0; i<=n; i++){
    c[0][i] = 0;
  }
  for(int i=1; i<=m; i++){
    for(int j=1; j<=n; j++){
      if(X[i-1] == Y[j-1]){
        c[i][j] = c[i-1][j-1] + 1;
      }else{
        c[i][j] = (c[i][j-1] > c[i-1][j] ? c[i][j-1] : c[i-1][j]);
      }
    }
  }
  return c[m][n];
}

int main(void){
  int q, l;
  string X, Y;
  cin >> q;
  for(int i=0; i<q; i++){
    cin >> X >> Y;
    l = lcs(X, Y);
    cout << l << endl;
  }
  return 0;
}

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

int main(){
  int n; cin >> n;
  for( int i = 0; i < n; i++ ){
    int dp[1010][1010];
    for( int i = 0; i < 1010; i++ ) dp[i][0] = dp[0][i] = 0;
    
    char x[1010], y[1010];
    cin >> x >> y;

    for( int i = 0; i < strlen( x ); i++ ){
      for( int j = 0; j < strlen( y ); j++ ){
	if( x[i] == y[j] ){
	  dp[i + 1][j + 1] = dp[i][j] + 1; 
	}else if( dp[i][j + 1] >= dp[i + 1][j] ){
	  dp[i + 1][j + 1] = dp[i][j + 1];
	}else{
	  dp[i + 1][j + 1] = dp[i + 1][j];
	}
      }
    }

    cout << dp[strlen( x )][strlen( y )] << endl;
  }
}

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

int lcs(string &X, string &Y) {
  int dp[1000 + 1][1000 + 1];
  int max = 0;
  int m = X.size();
  int n = Y.size();
  X = ' ' + X;
  Y = ' ' + Y;

  for (int i = 1; i <= m; i++)
    dp[i][0] = 0;

  for (int i = 1; i <= n; i++)
    dp[0][i] = 0;

  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; j++) {
      if (X[i] == Y[j])
	dp[i][j] = dp[i-1][j - 1] + 1;
      else if (dp[i - 1][j] >= dp[i][j - 1])
	dp[i][j] = dp[i - 1][j];
      else
	dp[i][j] = dp[i][j - 1];

      if(max < dp[i][j])
	max = dp[i][j];
    }
  }

  return max;
}

int main() {
  int N = 0;
  cin >> N;

  string X, Y;
  for (int i = 0; i < N; i++) {
    cin >> X >> Y;

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

  return 0;
}

C++: #include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;

int c[1010][1010];

void lcs(char X[], char Y[]){
	int m = strlen(X);
	int n = strlen(Y);
	int i, j;
	for(i = 1;i <= m;i++)
		c[i][0] = 0;
	for(j = 1;j <= m;j++)
		c[0][j] = 0;
	for(i = 1;i <= m;i++){
		for(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]);
		}
	}
}

int main(void){
	int q, i;
	char A[1000], B[1000];
	scanf("%d", &q);
	for(i = 0;i < q;i++){
		scanf("%s", A);
		scanf("%s", B);
		lcs(A, B);
		printf("%d\n", c[strlen(A)][strlen(B)]);
	}
	return 0;
}

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

int main(){
  int q;
  cin >> q;
  for(int m=0; m<q; m++){
    string wordx, wordy;
    cin >> wordx >> wordy;
    int L[1000][1000]={0};
    
    for(int j=0; j<wordy.size(); j++){
      for(int i=0; i<wordx.size(); i++){
	if(wordx[i]==wordy[j]){
	  L[i][j] = 1+L[i-1][j-1];
	}
	else{
	  L[i][j] = max(L[i][j-1], L[i-1][j]);
	}
      }
    }
    cout << L[wordx.size()-1][wordy.size()-1] << endl;
    
    
  }
}