Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
 
int lcs(string x, string y) {
    static int c[1001][1001];
    int m = x.size();
    int n = y.size();
    int max1 = 0;
    x = ' ' + x;
    y = ' ' + y;
    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] == y[j])c[i][j] = c[i - 1][j - 1] + 1;
            else c[i][j] = max(c[i - 1][j], c[i][j - 1]);
            max1 = max(max1, c[i][j]);
 
        }
    }
    return max1;
}
 
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 <iostream>
#include <string>
#include <algorithm>
using namespace std;
static const int MAX = 1001;
int L[MAX][MAX];

int LCS(string s1, string s2)
{
    int m = s1.size();
    int n = s2.size();
    for (int i = 0; i <= m; ++i)
    {
        L[i][0] = 0;
    }
    for (int i = 0; i <= n; ++i)
    {
        L[0][i] = 0;
    }
    for (int i = 1; i <= m; ++i)
    {
        for (int j = 1; j <= n; ++j)
        {
            if (s1[i-1] == s2[j-1])
            {
                L[i][j] = L[i-1][j-1] + 1;
            }
            else
            {
                L[i][j] = max(L[i-1][j], L[i][j-1]);
            }
        }
    }
    return L[m][n];
}

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 <stdio.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <math.h>
#include <string>

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

using namespace std;
int dp[1001][1001];
//?????????????????????
int n;
string x,y;
void solve(){
	cin >> n;
	REP(j,n){
	cin >> x >> y;
	memset(dp,0,1001*1001);
	int xn = x.size();
	int yn = y.size();
	REP(jj,xn+1){
		 REP(ii,yn+1){
			 if(jj <= 0 || ii <= 0){
				 dp[jj][ii] = 0 ;
			 }
			 else if(x[jj-1]==y[ii-1]) {
				 dp[jj][ii] = 1 + dp[jj-1][ii-1];
			 }
			 else{
				 dp[jj][ii] = max ( dp[jj-1][ii], dp[jj][ii-1] );
		   }
			 //cout << '('<<ii<<','<<jj<<')'<<dp[jj][ii]<<endl;
		 }

	}
	cout << dp[xn][yn]<<endl;
	}


}


int main(){
solve();
}

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

#define REP(i,x) for(int i{ 0 }; i < (int)(x); i++)

#define PB push_back
#define SZ(x) ((int)(x).size())

using namespace std;

typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<vector<int> > VVi;

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

int n;
Vs vs, vt;

int main()
{
	cin >> n;
	REP(_i, n)
	{
		string s, t;
		cin >> s >> t;
		vs.PB(s);
		vt.PB(t);
	}

	REP(_i, n)
	{
		string& s = vs[_i];
		string& t = vt[_i];
		
		VVi dp(SZ(s) + 1, Vi(SZ(t) + 1, 0));

		REP(i, SZ(s))
			REP(j, SZ(t))
		{
			chmax(dp[i + 1][j + 1], dp[i][j + 1]);
			chmax(dp[i + 1][j + 1], dp[i + 1][j]);
			if (s[i] == t[j])
				chmax(dp[i + 1][j + 1], dp[i][j] + 1);
		}

		cout << dp[SZ(s)][SZ(t)] << endl;
	}


}

C++: #include <stdio.h>
#include <iostream>
#include <utility>
#include <algorithm>
#include <math.h>
#include <vector>
using namespace std;
int dp[1001][1001] = {};

int getLCS(string X, string Y)
{
    int m = 0;
    for (int i = 1; i <= X.size(); i++)
    {
        for (int j = 1; j <= Y.size(); j++)
        {
            dp[i][j] = X[i - 1] == Y[j - 1] ? dp[i - 1][j - 1] + 1 : max(dp[i - 1][j], dp[i][j - 1]);
            m = max(m, dp[i][j]);
        }
    }
    return m;
}

int main()
{
    int q;
    string X, Y;
    cin >> q;
    for (int i = 0; i < q; i++)
    {
        cin >> X >> Y;
        cout << getLCS(X, Y) << "\n";
    }
    return 0;
}

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

using namespace std;
int n;

int main(void){
    // Your code here!
    string S, T;
    int dp[1001][1001];
    cin >> n;
    for(int c = 0; c < n; c++){
        cin >> S >> T;
        
        for(int i = 0; i <= S.size(); i++){
            dp[i][0] = 0;
        }
        for(int j = 0; j <= T.size(); j++){
            dp[0][j] = 0;
        }
        
        for(int i = 0; i < S.size(); i++){
            for(int j = 0; j < T.size(); j++){
                if(S[i]==T[j]) dp[i+1][j+1] = max({dp[i][j] + 1, dp[i][j+1], dp[i+1][j]});
                else dp[i+1][j+1] = max(dp[i][j+1], dp[i+1][j]);
            }
        }
        
        cout << dp[S.size()][T.size()] << endl;
    }
}