Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				} else {
					dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				}
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

C++: #include <iostream>
#include <vector>
using namespace std;
#define MAX_SEQ 1000

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

  for(int i=0;i<n;i++) {
    int subseq_len = 0;
    char seq1[MAX_SEQ+1];
    char seq2[MAX_SEQ+1];
    vector<char> seq_sub;
    cin >> seq1;
    cin >> seq2;

    for(int seq1_it=0;seq1[seq1_it]!='\0';seq1_it++) {
      vector<char>::iterator it = find(seq_sub.begin(), seq_sub.end(), seq1[seq1_it]);
        if (it == seq_sub.end()) {
          seq_sub.push_back(seq1[seq1_it]);
        }
    }
    for(int seq2_it=0;seq2[seq2_it]!='\0';seq2_it++) {
      vector<char>::iterator it = find(seq_sub.begin(), seq_sub.end(), seq2[seq2_it]);
        if (it != seq_sub.end()) {
          seq_sub.erase(it);
          subseq_len++;
        }
    }
    cout << subseq_len << endl;
  }
}

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

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

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

	for( int i = 0; i < q; i++ ) {
		string X, Y;
		cin >> X >> Y;
		int m = X.size();
		int n = Y.size();
		vector<vector<int>> c( m + 1, vector<int>( n + 1 ) );
		for( int j = 1; j < m + 1; j++ ) {
			for( int k = 1; k < n + 1; k++ ) {
				if( X[j - 1] == Y[k - 1] ) {
					c[j][k] = c[j - 1][k - 1] + 1;
				}
				else {
					c[j][k] = max( c[j][k - 1], c[j - 1][k] );
				}
			}
		}
		cout << c[m][n] << endl;
	}
}

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

int main() {
  uint32_t q = 0;
  std::cin >> q;
  while (q > 0) {
    q--;
    std::string X, Y;
    std::cin >> X >> Y;

    std::vector<std::vector<uint32_t>> dp(
        X.size() + 1, std::vector<uint32_t>(Y.size() + 1, 0));
    for (size_t i = 1; i < X.size() + 1; i++) {
      for (size_t j = 1; j < Y.size() + 1; j++) {
        dp[i][j] =
            (X[i - 1] == Y[j - 1] ? dp[i - 1][j - 1] + 1
                                  : std::max(dp[i][j - 1], dp[i - 1][j]));
      }
    }

    std::cout << dp.back().back() << std::endl;
  }

  return 0;
}

C++: #include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <vector>
#include <string>
#include <sstream>
#include <fstream>
#include <iostream>
#include <algorithm>
using namespace std;

int dat[1024][1024];
int getLcbLen(char* x, int xe, char* y, int ye){
	if(xe <= 0 || ye <= 0) return 0;
	if(dat[xe][ye] != -1) return dat[xe][ye];
	return dat[xe][ye] = (x[xe-1] == y[ye-1] ? 1 + getLcbLen(x, xe-1, y, ye-1) : max(getLcbLen(x, xe-1, y, ye), getLcbLen(x, xe, y, ye-1)));
}

int main() {
	int set;
	scanf("%d", &set);
	
	while(set--){
		char x[1024], y[1024];
		scanf("%s %s", x, y);
		
		for(int i = 0; i < 1024; i++){
			for(int k = 0; k < 1024; k++){
				dat[i][k] = -1;
			}
		}
		printf("%d\n", getLcbLen(x, (int)strlen(x), y, (int)strlen(y)));
	}
	return 0;
}