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

#if __has_include("print.hpp")
  #include "print.hpp"
#endif

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

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

vector<vector<int>> dp(2000, vector<int>(2000));

void solve(string s, string t){
  int n = int(s.size());
  int m = int(t.size());

  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if(s[i] == t[j]){
        dp[i+1][j+1] = dp[i][j] + 1;
      }else{
        dp[i+1][j+1] = max(dp[i][j+1], dp[i+1][j]);
      }
    }
  }

  cout << dp[n][m] << endl;
}

int main(){
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
  {
    string s, t;
    cin >> s >> t;
    solve(s, t);
  }
}

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

int lcs(string str1, string str2){
  int C[1001][1001];
  int maxl = 0;

  str1 = ' ' + str1;
  str2 = ' ' + str2;

  for(int i = 1 ; i <= str1.size() ; i++) C[i][0] = 0;
  for(int j = 1 ; j <= str2.size() ; j++) C[0][j] = 0;

  for(int i = 1 ; i <= str1.size()-1 ; i++){
    for(int j = 1 ; j <= str2.size()-1 ; j++){
     
      if(str1[i] == str2[j]) C[i][j] = C[i - 1][j - 1] + 1;
      else if(C[i - 1][j] >= C[i][j -1]) C[i][j] = C[i - 1][j];
      else C[i][j] = C[i][j - 1];

      if(C[i][j] >= maxl) maxl = C[i][j];

    }
  }

  return maxl;
}

int main(){
  string str1, str2;
  int n;

  cin >> n;

  for(int i = 0 ; i < n ; i++){
    cin >> str1 >> str2;
    cout << lcs(str1, str2) << endl;
  }

  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][N];
  int m = X.size();
  int n = Y.size();

  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      if (X[i] == Y[j]) 
        if (i == 0 || j == 0) 
          c[i][j] = 1;
        else 
          c[i][j] = c[i - 1][j - 1] + 1;
      else
        c[i][j] = max(c[i][j - 1], c[i - 1][j]);
    }
  }
  return c[m - 1][n - 1];
}

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++: /*
    Problem 38
    https://onlinejudge.u-aizu.ac.jp/problems/ALDS1_10_C
*/
#include <bits/stdc++.h>
using namespace std;
/* typedef */
typedef long long ll;
typedef pair<int, int> pii;
/* constant */
const int INF = 1 << 30;
const ll LINF = 1LL << 50;
const int NIL = -1;
const int MAX = 1005;
const int mod = 1000000007;
const double pi = 3.141592653589;
/* global variables */
vector<vector<int>> dp(MAX, vector<int>(MAX));
/* function */
void calc(string s, string t) {
    int S = s.size(), T = t.size();
    // init
    for (int i = 0; i < S; i++) for (int j = 0; j < T; j++) dp[i][j] = 0;
    for (int i = 0; i < S; i++) {
        for (int j = 0; j < T; j++) {
            dp[i+1][j+1] = max(dp[i+1][j], dp[i][j+1]);
            if (s[i] == t[j]) dp[i+1][j+1] = dp[i][j] + 1;
        }
    }
    cout << dp[S][T] << '\n';
}
/* main */
int main(){
    int n;
    cin >> n;
    string s, t;
    for (int i = 0; i < n; i++) {
        cin >> s >> t;
        calc(s, t);
    }
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <set>
#include <algorithm>
#include <array>
#include <complex>
#include <utility>
#include <map>
#include <inttypes.h>

int LCS(std::string s,std::string t){
    int n,m,c[n+1][m+1];
    n=s.size();
    m=t.size();
    int maxlen=0;
    for(int i=0;i<n;i++){
        c[i][0]=0; 
    }
    for(int i=0;i<m;i++){
        c[0][i]=0;
    }
    for(int i=0;i<n;i++){
        for(int j=0;j<m;j++){
            if(s[i]==t[i]){
                c[i][j]=c[i-1][j-1]+1;
            }else{
                c[i][j]=std::max(c[i-1][j],c[i][j-1]);
            }
            maxlen=std::max(c[i][j],maxlen);
        }
    }
    return max
}
int main(){
	int N;
    
    std::cin >> N;
    std::string s1,s2;
    for(int i=0;i<N;i++){
        std::cin >> s1 >> s2;
        std::cout << LCS(s1,s2) <<std::endl;
    }
        
    
    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <math.h>
#include <map>
#include <functional>
#include <iomanip>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <typeinfo>
#define PI 3.14159265359
#define INF 99999999;
#define rep(i, n) for(int i=0; i<n; i++)
#define REP(n) rep(i, n)
#define EPS 1e-10
typedef long long ll;
using namespace std;
typedef pair<int, int> P;

double distanceAB(double xa, double ya, double xb, double yb);
void trace(int A[], int N);

/*
class Target
{
public:
	vector <string> draw(int n)
	{

	}
};
*/


static const int N = 1000;
int c[N + 1][N + 1];

int lcs(string X, string Y)
{
	int m = X.size();
	int n = Y.size();
	int maxl = 0;
	X = ' ' + X;
	Y = ' ' + Y;
	for (int i=1; 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;
	REP(n)
	{
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << endl;
	}
	
	return 0;
}


void trace(int A[], int N)
{
	REP(N)
	{
		if (i > 0) cout << " ";
		cout << A[i];
	}
	cout << endl;
}


double distanceAB(double xa, double ya, double xb, double yb)
{
	return sqrt((xb-xa)*(xb-xa) + (yb-ya)*(yb-ya));
}

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

int dp[1010][1010];

int main() {
	int q;
	cin >> q;
	vector<string> x(q), y(q);
	for (int i = 0;i < q;i++) {
		cin >> x[i] >> y[i];
	}

	for (int i = 0;i <= 1000;i++) {
		dp[i][0] = 0;
		dp[0][i] = 0;
	}
	for (int i = 0;i < q;i++) {
		for (int j = 1;j <= x[i].size();j++) {
			for (int k = 1;k <= y[i].size();k++) {
				dp[j][k] = max(dp[j - 1][k], dp[j][k - 1]);
				if (x[i][j] == y[i][k]) {
					dp[j][k] = max(dp[j][k], dp[j - 1][k - 1] + 1);
				}
			}
		}
		cout << dp[x[i].size()][y[i].size()] << endl;
	}

	return 0;
}