Go: package main

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

func max(x, y int) int {
	if x < y {
		return y
	} else {
		return x
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		scanner.Scan()
		s1 := scanner.Text()
		scanner.Scan()
		s2 := scanner.Text()
		s1, s2 = " " + s1 , " " + s2
		c := make([][]int, len(s1))
		for i := range c {
			c[i] = make([]int, len(s2))
		}

		LCS := 0

		for i := 1; i < len(s1); i++ {
			for j := 1; j < len(s2); j++ {
				if s1[i] == s2[j] {
					c[i][j] = c[i-1][j-1] + 1
				} else {
					c[i][j] = max(c[i-1][j], c[i][j-1])
				}
				LCS = max(LCS, c[i][j])
			}
		}
		fmt.Println(LCS)
	}
}

C++: #include <stdio.h>
#include <vector>
#include <list>
#include <map>
#include <array>
#include <memory>
#include <string>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <cmath>
#include <unordered_map>
#include <stdexcept>


using std::string;
using std::vector;


//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// util
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

std::vector<std::string> split(const std::string& input, char delimiter)
{
    std::istringstream stream(input);

    std::string field;
    std::vector<std::string> result;
    while (std::getline(stream, field, delimiter)) {
        result.push_back(field);
    }
    return result;
}



//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// user func
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

void printList(const vector<int>& list) {
    // print
    for(int i = 0; i < list.size(); i++){
        printf(" %d", list[i]);
    }
    printf("\n");
}



//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// logic
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

// Longest Common Subsequence
int LCS(const string& x, const string& y) {
    int result = 0;
    vector<vector<int>> table(x.length() + 1, vector<int>(y.length() + 1, 0));
    
    for (int i = 1; i <= x.length(); i++) {
        for (int j = 1; j <= y.length(); j++) {
            if (x[i-1] == y[j-1]) {
                table[i][j] += table[i-1][j-1] + 1;
            } else {
                table[i][j] = std::max(table[i-1][j], table[i][j-1]);
            }
            result = std::max(result, table[i][j]);
        }
    }
    return result;
}

void solve() {
    int n;
    scanf("%d", &n);
    for(int i = 0; i < n; i++){
        char bufX[1024];
        char bufY[1024];
        scanf("%s", bufX);
        scanf("%s", bufY);
        printf("%d\n", LCS(string(bufX), string(bufY)));
    }
}


//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// main
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
int main() {
    solve();
    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=0;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 s1,s2;
  int n; cin >> n;
  for(int i=0;i<n;i++)
    {
      cin>>s1>>s2;
      cout<<lcs(s1,s2)<<endl;
    }
  return 0;
}

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

int main(void){
  int q;
  cin >> q;

  for(int i=0; i<q; i++){
    string x, y;
    cin >> x >> y;
    
    int nx, ny;
    nx = x.size();
    ny = y.size();
    
    vector< vector<int> > lcs(nx+1, vector<int>(ny+1, 0));

    for(int i=1; i<=nx; i++){
      for(int j=1; j<=ny; j++){
	if(x[i-1] == y[j-1])
	  lcs[i][j] = lcs[i-1][j-1] + 1;
	else
	  lcs[i][j] = max(lcs[i-1][j], lcs[i][j-1]);
      }
    }
    
    cout << lcs[nx][ny] << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <string>
#define repi(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,a) repi(i,0,a)
#define clr(a,v) memset((a),(v),sizeof(a))

int q;
int dp[1000][1000];
std::string s, t;

int rec( int i, int j )
{
  int &ret = dp[i][j];

  if( ~ret )
    return ret;

  if( i == s.size() || j == t.size() )
    return 0;

  ret = 0;

  if( s[i] == t[j] )
    ret = std::max( ret, rec( i+1, j+1 )+1 );

  ret = std::max( ret, std::max( rec( i+1, j ), rec( i, j+1 ) ) );

  return ret;
}

int main()
{
  scanf( "%d", &q );
  while( q-- )
  {
    std::cin >> s >> t;

    clr( dp, -1 );

    std::cout << rec( 0, 0 ) << std::endl;
  }

  return 0;
}

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



auto lcs(const std::string& a, const std::string& b, std::vector<std::vector<int> >*tp) {
	auto tab = *tp;

	for (auto&e : tab) {
		std::fill(std::begin(e),std::end(e),0);
	}

	for (decltype(a.size()) ai{1}; ai <= a.size();++ai) {
		for (decltype(ai) bi{1}; bi<=b.size(); ++bi) {
			if (a[ai-1] == b[bi-1])
				tab[ai][bi] = tab[ai - 1][bi - 1] + 1;
			else
				tab[ai][bi] = std::max(tab[ai - 1][bi], tab[ai][bi - 1]);
		}
	}
	return tab[a.size()][b.size()];
}

int main() {
	int q;
	std::cin >> q;

	std::vector<std::vector<int>> buf{};
	buf.resize(1005);
	for (auto&e : buf)
		e.resize(1005);

	for (int i{}; i < q; ++i) {
		std::string x, y;
		std::cin >> x >> y;
		std::cout << lcs(x, y, &buf)<<"\n";
	}

	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

typedef long long ll;

#define FOR(index, init, max) for (int index = (init); index < (max); i++)
#define REP(index, max) for (int index = 0; index < (max); i++)
#define FOREACH(x, array) for (auto&& (x) : array)
#define VECCIN(vec) for (auto&& vec_i : vec) cin >> vec_i
#define VECCOUT(vec) for (const auto& vec_i : vec) cout << vec_i << endl

int main() {
    int q;
    cin >> q;

    int dp[1001][1001] = {0};

    while(q > 0) {
        string x, y;
        cin >> x >> y;

        for (int x_i = 0; x_i < x.length(); x_i++) {
            for (int y_i = 0; y_i < y.length(); y_i++) {
                if (x[x_i] == y[y_i]) {
                    dp[x_i + 1][y_i + 1] = dp[x_i][y_i] + 1;
                }
                else {
                    dp[x_i + 1][y_i + 1] = max(dp[x_i][y_i + 1], dp[x_i + 1][y_i]);
                }
            }
        }

        cout << dp[x.length()][y.length()] << endl;
        q--;
    }

    return 0;
}