Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func lcs(a, b string) int {
	lenA := len(a)
	lenB := len(b)
	dp := make([][]int, lenA+1)
	for i := range dp {
		dp[i] = make([]int, lenB+1)
	}

	for i := 1; i <= lenA; i++ {
		for j := 1; j <= lenB; j++ {
			if a[i-1] == b[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[lenA][lenB]
}

func main() {
	n := scanInt()
	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		a := scanString()
		b := scanString()
		fmt.Fprintln(w, lcs(a, b))
	}
	w.Flush()
}

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

using namespace std;

//I can't understand,so I imitated yutaka watabe's book.
//I think this problem has 5 star rank difficulty.

void calc(char X[],char Y[]){
	int X_length=0,Y_length=0;
	int** table = new int*[1001];
	for(int i = 0; i < 1001; i++){
		table[i] = new int[1001];
		for(int k = 0; k < 1001; k++)table[i][k] = 0;
	}
	for(int i = 0; X[i] != '\0'; i++)X_length++;
	for(int i = 0; Y[i] != '\0'; i++)Y_length++;
	int max_succeed = 0;
	for(int i = 0; i < X_length; i++){
		for(int k = 0; k < Y_length; k++){
			if(X[i] == Y[k]){
				table[i+1][k+1] = table[i][k] + 1;
			}else{
				table[i+1][k+1] = max(table[i+1][k],table[i][k+1]);
			}
			max_succeed = max(max_succeed,table[i+1][k+1]);
		}
	}
	printf("%d\n",max_succeed);
}

int main(){
	int q;
	char X[1001],Y[1001];
	scanf("%d",&q);
	for(int i=0;i<q;i++){
		scanf("%s %s",X,Y);
		calc(X,Y);
	}
    return 0;
}

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

const int Size = 1000;
int dp[Size + 1][Size + 1];
std::string x;
std::string y;

int calc(int m, int n)
{
	int ans = 0;

	if (dp[m][n] != -1) {
		return dp[m][n];
	}

	if (m == 0 || n == 0) {
		return 0;
	}

	if (x[m - 1] == y[n - 1]) {
		ans = calc(m - 1, n - 1) + 1;
		dp[m][n] = ans;
		return ans;
	}

	ans = std::max(calc(m, n - 1), calc(m - 1, n));
	dp[m][n] = ans;
	return ans;
}


int main()
{
	int q;
	std::vector<int> ans;
	std::cin >> q;

	for (int i = 0; i < q; i++) {
		std::cin >> x >> y;
		for (int j = 0; j < Size + 1; j++) {
			for (int k = 0; k < Size + 1; k++) {
				dp[j][k] = -1;
			}
		}
		int temp = calc(x.size(), y.size());
		ans.push_back(temp);
	}

	for (unsigned int i = 0; i < ans.size(); i++) {
		std::cout << ans[i] << std::endl;
	}

	return 0;
}

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

#define ll long long
#define vvi vector<vector<int>>
#define vec vector
#define pq priority_queue
#define all(v) (v).begin(), (v).end()
#define uniqueV(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());
#define rep(i, n) for (int (i) = (0); (i) < (n); ++(i))
#define repp(i, m, n) for (int (i) = (m); (i) < (n); ++(i))
#define dbg(x) cerr << #x << ": " << x << endl;
#define dbg2(x, y) cerr<<"("<<#x<<", "<<#y<<") = "<<"("<<x<<", "<<y<<")"<<endl;
#define dbg3(x, y, z) cerr<<"("<<#x<<", "<<#y<<", "<<#z<<") = "<<"("<<x<<", "<<y<<", "<<z<<")"<<endl;
#define dbgB(value, size) cerr<<#value<<": "<<bitset<size>(value) << endl;
#define line() cerr << "---------------" << endl;

const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const double PI = 3.14159265358979323846;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }

template<typename T>
void printA(vector<T> &printArray, char between = ' ') {
   int paSize = printArray.size();
   for (int i = 0; i < paSize; i++) { cerr << printArray[i] << between;}
   if (between != '\n') {cerr << endl;}
}

// ------------------------------------------------------------------------------------------

int q;
string x, y;
int dp[1111][1111];

void solve() {
   for (int i = 1; i <= x.size(); i++) {
      for (int j = 1; j <= y.size(); j++) {
         if (x[i] == y[j]) {
            dp[i][j] = dp[i-1][j-1] + 1;
         } else {
            dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
         }
      }
   }
   cout << dp[x.size()][y.size()] << endl;
}

int main() {
   cin >> q;
   while (q--) {
      cin >> x >> y;
      solve();
   }

   return 0;
}

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

int max(int a, int b) { return a < b ? b : a; }

int lcs(string x, string y) {
    int c[1001][1001] = {0};
    int m = x.size();
    int n = y.size();
    int maxl = 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]);
            }
            maxl = max(maxl, c[i][j]);
        }
    }

    return maxl;
}

int main() {

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

    return 0;
}

C++: #include <iostream>

int main()
{
    int num;
    std::cin >> num;
    std::string a, b;
    while (std::cin >> a >> b) 
    {
        int m, n;
        m = a.size();
        n = b.size();
        a = ' ' + a;
        b = ' ' + b;
        int maxl = 0;
        long c[m + 1][n + 1];
        for (int i = 0; i <= m; i++) c[i][0] = 0;
        for (int i = 1; i <= n; i++) c[0][i] = 0;
        for (int i = 1;  i <= m; i++) 
        {
            for (int  j = 1; j <= n; j++)
            {
                if (a[i] == b[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];
                maxl = (maxl >= c[i][j]) ? maxl : c[i][j];
            }
        }
        std::cout << maxl << '\n';
    }
}

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


int main() {
    int q;
    cin >> q;
    for (int i = 0; i < q; ++i) {
        string s, t;
        cin >> s >> t;
        int sl = s.size(), tl = t.size();
        int dp[1010][1010];
        dp[0][0] = 0;
        for (int j = 1; j <= sl; ++j) {
            for (int k = 1; k <= tl; ++k) {
                if (s[j - 1] == t[k - 1]) {
                    dp[j][k] = dp[j - 1][k - 1] + 1;
                }
                else {
                    dp[j][k] = max(dp[j - 1][k], dp[j][k - 1]);
                }
            }
        }
        cout << dp[sl][tl] << "\n";
    }
    return 0;
}