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<vector>
//#include<algorithm>

const static int MAX = 1001;
std::string X, Y;
int LCS[MAX][MAX];

int main(void){
    int q, x_size, y_size;
    std::cin >> q;
    for(int i = 0; i < q; i++){
	std::cin >> X >> Y;
	LCS[0][0] = 0;
	LCS[0][1] = 0;
	LCS[1][0] = 0;
	x_size = X.size();
	y_size = Y.size();
	for(int j = 0; j < X.size(); j++){
	    for(int k = 0; k < Y.size(); k++){
		if(X[j] == Y[k]){
		    LCS[j+1][k+1] = LCS[j][k] + 1;
		}else if(X[j] != Y[k]){
		    LCS[j+1][k+1] = std::max(LCS[j][k+1], LCS[j+1][k]);
		}
	    }
	}
	std::cout << LCS[x_size][y_size] << std::endl;
    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vl vector<ll>
#define pl pair<ll,ll>
#define rep(i,b) for(ll i=0;i<b;i++)
#define all(v) (v).begin(),(v).end()

ll lcs(string X,string Y){
    ll c[1001][1001];
    ll m=X.size();
    ll n=Y.size();
    ll 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<=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;
ll n;cin>>n;
rep(i,n){
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<endl;
}
}

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

static int N=1000;

int lcs(string x,string y){
  int num[N+5][N+5];
  int ans=0;
  int leng_x=x.size();
  int leng_y=y.size();  
  
  x=' '+x;
  y=' '+y;

  for(int i=1;i<=leng_x;i++)num[i][0]=0;
  for(int i=1;i<=leng_y;i++)num[0][i]=0;
  

  for(int i=1;i<=leng_x;i++){
    for(int j=1;j<=leng_y;j++){
      if(x[i]==y[j]) num[i][j]=num[i-1][j-1]+1;
      else num[i][j]=max(num[i][j-1],num[i-1][j]);
      ans=max(ans,num[i][j]);
    }
  }
  return ans;
}

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>
using namespace std;
inline void chmax (int& a, int b) {
  if (a < b) a = b;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int q;
  cin >> q;
  while (q--) {
    string x, y;
    cin >> x >> y;
    int m = x.length();
    int n = y.length();
    vector<int> dp(n + 1, 0);
    for (int i = 1; i <= m; i++) {
      for (int j = 1; j <= n; j++) {
        chmax(dp[j], dp[j - 1]);
        if (x[i - 1] == y[j - 1]) dp[j] = dp[j - 1] + 1;
      }
    }
    int ret = dp[n];
    cout << ret << '\n';
  }
  return 0;
}