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<algorithm>
#include<string>

using namespace std;

int main () {

    int N, m, n, i, j, k, c[1001][1001];
    string x, y;

    cin >> N;

    for (k = 0; k < n; k++) {
        cin >> x >> y;
        m = x.size ();
        n = y.size ();

        for (i = 1; i < m + 1; i++) {
            for (j = 1; j <= n + 1; j++) {

                if (x[i - 1] == y[j - 1]) {
                    c[i][j] = c[i - 1][j - 1] + 1;
                } else {
                    c[i][j] = max (c[i - 1][j], c[i][j - 1]);
                }

            }
        }

    cout << c[m][n] << endl;

    }

}

C++: #include <iostream>
#include <string>
#include <string.h>

using namespace std;

int main(int argc, char* argv[]) {
  int q;
  cin >> q;
  int rets[q];
  for (int i = 0; i < q; ++i) {
    string s, t;
    cin >> s >> t;

    int dp[s.size() + 1][t.size() + 1];
    memset(dp, 0, sizeof(int) * (s.size() + 1) * (t.size() + 1));

    for (int j = 0; j < s.size(); ++j) {
      for (int k = 0; k < t.size(); ++k) {
        if (s[j] == t[k])
          dp[j + 1][k + 1] = dp[j][k] + 1;
        else
          dp[j + 1][k + 1] = max(dp[j + 1][k], dp[j][k + 1]);
      }
    }

    rets[i] = dp[s.size()][t.size()];

  }

  for (int i = 0; i < q; ++i)
    cout << rets[i] << endl;

  return 0;
}

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

using namespace std;

void lcs(string x,string y){
  int m=x.length();
  int n=y.length();
  int c[m+1][n+1];
  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-1]==y[j-1]){
        c[i][j]=c[i-1][j-1]+1;
      }else{
        c[i][j]=max(c[i-1][j],c[i][j-1]);
      }
    }
  }
  cout << c[m][n] << endl;
}

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

C++: #include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <stack>
#include <queue>
#include <deque>
#include <iomanip>
#include <string>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <tuple>
#include <bitset>

/*----------------------------------------------------------------*/

using ld = long double;
using vld = std::vector<ld>;
using ll = long long;
using vll = std::vector<ll>;
using vvll = std::vector<vll>;
using str = std::string;
using vstr = std::vector<str>;
using vb = std::vector<bool>;
using vvb = std::vector<vb>;

/*----------------------------------------------------------------*/

template<typename T> bool chmin(T a, T &b) { return a < b ? b = a, true : false; }
template<typename T> bool chmax(T a, T &b) { return a > b ? b = a, true : false; }
template<typename T> T sqr(T a) { return a * a; }

/*----------------------------------------------------------------*/

constexpr ld PI = 3.141592653589793L;
constexpr ld EPS = std::numeric_limits<ld>::epsilon();

/*----------------------------------------------------------------*/

ll gcd(ll n, ll m) { return m != 0 ? gcd(m, n % m) : n; }
ll lcm(ll n, ll m) { return n / gcd(n, m) * m; }
bool is_prime(ll n) {
    if (n == 1) return false;
    for (ll i = 2; sqr(i) <= n; i++)
        if (n % i == 0) return false;
    return true;
}
ll popcnt(ll n) {
    n = ((n & 0xaaaaaaaaaaaaaaaa) >> 1) + (n & 0x5555555555555555);
    n = ((n & 0xcccccccccccccccc) >> 2) + (n & 0x3333333333333333);
    n = ((n & 0xf0f0f0f0f0f0f0f0) >> 4) + (n & 0x0f0f0f0f0f0f0f0f);
    n = ((n & 0xff00ff00ff00ff00) >> 8) + (n & 0x00ff00ff00ff00ff);
    n = ((n & 0xffff0000ffff0000) >> 16) + (n & 0x0000ffff0000ffff);
    n = ((n & 0xffffffff00000000) >> 32) + (n & 0x00000000ffffffff);
    return n;
}

/*----------------------------------------------------------------*/

void solve();

/*----------------------------------------------------------------*/

int main() {
    std::cin.tie(0);
    std::ios::sync_with_stdio(false);
    std::cout << std::setprecision(15);

    solve();
}

void solve() {
    ll q; std::cin >> q;

    for (ll i = 0; i < q; i++) {
        str x, y; std::cin >> x >> y;
        ll x_len = x.length(), y_len = y.length();
        vvll dp(x_len + 1, vll(y_len + 1, 0));
        for (ll i = 1; i <= x_len; i++) for (ll j = 1; j <= y_len; j++)
            if (x[i - 1] == y[j - 1])
                dp[i][j] = dp[i - 1][j - 1] + 1;
            else
                dp[i][j] = std::max(dp[i - 1][j], dp[i][j - 1]);
        std::cout << dp[x_len][y_len] << '\n';
    }
}

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

int lcs(string &X, string &Y)
{
	static int Z[1001][1001];
	int m = X.size();
	int n = Y.size();
	int i, j;

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

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);

	string X, Y;
	int q;
	scanf("%d", &q);
	for (int i = 0; i < q; i++) {
		cin >> X >> Y;
		cout << lcs(X, Y) << endl;
	}
	return 0;
}

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

int main(){
  int n;
  char x[1001],y[1001];
  int dp[1002][1002];
  


  //load n;
  cin >>n;
  for(int i=0;i<n;i++){
    //initialize
    for(int i=0;i<1002;i++){
      for(int j=0;j<1002;j++){
	dp[i][j]=0; 
      }
    }
    //load string
    scanf("%s",x);
    scanf("%s",y);
    //dp
    for(int j=0;j<strlen(x);j++){
      for(int k=0;k<strlen(y);k++){
	if(x[j]==y[k]){
	  dp[j+1][k+1]=dp[j][k]+1;
	}

	else{
 
	  if(dp[j][k+1]>dp[j+1][k]){
	    dp[j+1][k+1]=dp[j][k+1];
	  }

	  else{
	    dp[j+1][k+1]=dp[j+1][k];
	  }
	}
      }
    }

    //print
    cout <<dp[strlen(x)][strlen(y)]<<endl;
  }



  return 0;
}