Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

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

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

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=0; j<=n; j++) c[0][j] = 0;

	for (int i = 1; i <= n; i++){
		for (int j = 1; j <= m; j++){
			if (X[i] == Y[j]){
				c[i][j] = c[i-1][j-1] + 1;
			} else{
				c[i][j] = max(c[i][j-1], c[i-1][j]);
			}
			maxl = max(maxl, c[i][j]);
		}
	}

	return maxl;

}

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

}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < n; i++)
#define pb push_back
using namespace std;
typedef long long ll;

int main(){
  int n;
  cin>>n;
  
  rep(i,n){  
    string a,b;
    cin>>a>>b;
    
    int dp[1005][1005];
    rep(i,1005)rep(j,1005)dp[i][j] = 0;
    
    rep(j,a.size())rep(k,b.size()){
      if(a[j]==b[k]) dp[j+1][k+1] = max(dp[j+1][k+1],dp[j][k]+1);
      else dp[j+1][k+1] = max(max(dp[j][k+1],dp[j+1][k]),dp[j+1][k+1]);
    }
    
    cout << dp[a.size()][b.size()] << endl;
  }
}

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

typedef pair<int,int> P;
typedef long long ll;

#define rep(i,n) for(int i=1;i<=n;i++)
#define pb push_back 
#define inf INT_MAX/4 
#define ALL(v) v.begin(),v.end()
#define N 1001

int c[N][N];

int lcs(string X, string Y){
  int lx = X.size();
  int ly = Y.size();
  int ans = 0;

  X = ' ' + X;
  Y = ' ' + Y;

  rep(i,lx) rep(j,ly) c[i][j] = 0;

  rep(i,lx){
   rep(j,ly){
    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]);
    }
    ans = max(ans, c[i][j]);
   }
  }

  return ans;
}

int main(void){

  int q;

  cin >> q;

  while(q--){
    string X, Y;
    cin >> X >> Y;

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

  return 0;
}