Go: package main

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

type Position struct {
	X int
	Y int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}
	for i := 0; i < n; i++ {
		strX := nextText(sc)
		strY := nextText(sc)
		fmt.Println(calcLcs(strX, strY))
	}
}

func calcLcs(strX, strY string) int {
	return lcs(strX, strY, Position{0, 0}, make(map[Position]int))
}

func lcs(strX string, strY string, position Position, memo map[Position]int) int {
	if position.X >= len(strX) || position.Y >= len(strY) {
		return 0
	}
	if v, ok := memo[position]; ok {
		return v
	}
	if strX[position.X] == strY[position.Y] {
		result := lcs(strX, strY, Position{position.X + 1, position.Y + 1}, memo)
		memo[position] = result + 1
		return memo[position]
	} else {
		result1 := lcs(strX, strY, Position{position.X + 1, position.Y}, memo)
		result2 := lcs(strX, strY, Position{position.X, position.Y + 1}, memo)
		var result int
		if result1 > result2 {
			result = result1
		} else {
			result = result2
		}
		memo[position] = result
		return result
	}
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int,int>;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define INF 10**9

int main() {
    int n,sx,sy;
    string x,y;
    cin >> n;
    rep(i,n){
        cin >> x >> y;
        sx = x.size();
        sy = y.size();
        vector<vector<int>> c(sy+1,vector<int>(sx+1));
        rep(j,sy+1)rep(k,sx+1) c.at(j).at(k) = -1;
        rep(j,sy+1)rep(k,sx+1){
            if (j==0 or k==0){
                c.at(j).at(k) = 0;
            }
            else if (x.at(k-1) == y.at(j-1)){
                c.at(j).at(k) = c.at(j-1).at(k-1) + 1;
            }
            else {
                c.at(j).at(k) = max(c.at(j).at(k-1),c.at(j-1).at(k));
            }
        }
        cout << c.at(sy).at(sx) << endl;
    }
}

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

using namespace std;


int main(){

  string str;
  string str2;
  int n,s,s2;
  int cou[1024][1024] = {{}};
  int max = 0;

  cin >> n;

  for(int i = 0;i < n;i++){

    cin >> str >> str2;

    str = ' ' + str;
    str2 = ' ' + str2;


    s = str.size();
    s2 = str2.size();

    for(int j = 1;j < s;j++){
      for(int k = 1;k < s2;k++){
	if(str[j] == str2[k]){
	  cou[j][k] = cou[j - 1][k - 1] + 1;
	  if(cou[j][k] > max) max = cou[j][k];
	  // cout << "a: str = " << str[j] << " str2 = " << str2[k] << " cou = " << cou[j][k] << endl;
	}
	else if(cou[j - 1][k] > cou[j][k - 1]){
	  cou[j][k] =  cou[j - 1][k];
	  // cout << "str = " << str[j] << " str2 = " << str2[k] << " cou = " << cou[j][k] << endl;
	}
	else {
	  cou[j][k] = cou[j][k - 1];
	  // cout << "str = " << str[j] << " str2 = " << str2[k] << " cou = " << cou[j][k] << endl;
	}
      }
    }


    cout << max << endl;
      
    max = 0;

    for(int j = 0;j <= s;j++){
      for(int k = 0;k <= s2;k++){
	cou[j][k] = 0;
      }
    }
  }
}

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

using namespace std;

int dp[1010][1010];



int solve() {

	string s,t;

	cin >> s >> t;


	int max_s = s.length();
	int max_t = t.length();

	memset(dp,0, sizeof(int) * 1010 * 1010);



	for (int i = 1; i <= max_s; i++) {
		for (int j = 1; j <= max_t; j++) {
			if (s.at(i - 1) == t.at(j -1)) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			} else {
				dp[i][j] = max(dp[i][j - 1],dp[i -1][j]);			
			}
		}
	}
	return dp[max_s][max_t];
}

int main() {
	int q;

	cin >> q;

	for (int i = 0; i  < q; i++) {
		cout << solve() << endl;
	}

}

C++: //#if 0
//????????????????§£?????????????????????????????????????????????????????????C++??§string??????????????§???
//?????????????????§???????????§???AOJ?????????????????????Runtime Error??????????????????????????????
//??£????????¨??????????????????????????????????????????????????????Runtime Error???????????¨???????????????
//??§???????????????????????????????????§???
//#endif
#include<iostream>
#include<string>
#define lth 1010

using namespace std;

int main()
{
	int n, L[1010][1010], Lmax = 0, *save;
	string *Xi, *Yi;
	cin >> n;
	save = new int[n];

		Xi = new string[lth];
		Yi = new string[lth];
	

	for (int k = 0; k < n; k++)
	{
		Lmax = 0;
		string X, Y;
		cin >> X >> Y;
		for (int i = 0; i <= X.length(); i++)
		{
			if (i != 0)
				Xi[i] = X.substr(0, i );
		}
		for (int i = 0; i <= Y.length(); i++)
		{
			if (i != 0)
				Yi[i] = Y.substr(0, i );
		}
		for (int i = 0; i <= X.length(); i++)
			for (int j = 0; j <= Y.length(); j++)
			{
				if (i == 0 || j == 0)
					L[i][j] = 0;
				else if (Xi[i][i - 1] == Yi[j][j - 1])
				{
					L[i][j] = L[i - 1][j - 1] + 1;
				}
				else
				{
					L[i][j] = (L[i][j - 1] > L[i - 1][j]?L[i][j - 1] : L[i - 1][j]);
				}
				if (Lmax < L[i][j]) Lmax = L[i][j];
			}
		save[k] = Lmax;
	}

	for (int i = 0; i < n; i++)
		cout << save[i] << endl;
}

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

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

static const int N = 10000;

int lcs(string X, string Y);

int main(void){
	string s1, s2;
	int n; cin >> n;
	int i;
	REP(i, n) {
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}

// longest common sequence
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;
	int i, j;
	FOR(i, 1, m + 1) FOR(j, 1, n + 1) {
		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;
}

C++: #include <array>
#include <vector>
#include <deque>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <string>
#include <algorithm>
#include <numeric>
#include <functional>
#include <iterator>
#include <tuple>
#include <utility>
#include <limits>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cstdint>
#include <cassert>

using namespace std;

#define FOR(i, start, end) for(int i = (start); i < (end); ++i)
#define REP(i, n) FOR(i, 0, n)

constexpr int N = 1000;

int dp[N+1][N+1];

int solve(const string& x, const string& y)
{
    int m = x.size();
    int n = y.size();

    FOR(i, 0, m+1)
        dp[i][0] = 0;
    FOR(j, 0, n+1)
        dp[0][j] = 0;

    FOR(i, 1, m+1) {
        FOR(j, 1, n+1) {
            if(x[i-1] == y[j-1])
                dp[i][j] = dp[i-1][j-1] + 1;
            else
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
        }
    }

    return dp[m][n];
}

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

    REP(_, n) {
        string x, y;
        cin >> x;
        cin >> y;

        int lcs_len = solve(x, y);
        cout << lcs_len << "\n";
    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for (int i = 0; i < n; i++)
typedef long long ll;
// Welcome to my source code!

int lcs(string x, string y) {
    int m = x.size();
    int n = y.size();
    int c[m+1][n+1] = {};
    int maxv = 0;
    x = ' ' + x;
    y = ' ' + y;
    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]);
            }
            maxv = max(maxv, c[i][j]);
        }
    }
    return maxv;
}

int main() {
    int q;
    string x, y;
    cin >> q;
    REP(i,q) {
        cin >> x >> y;
        cout << lcs(x,y) << endl;
    }
}