Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

C++: #include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
using namespace std;

#define N_MAX 1000

char X[N_MAX];
char Y[N_MAX];
char LCS[N_MAX][N_MAX];


int longest(int x, int y)
{
    for (int i = 0; i < x+1; i++) {
        for (int j = 0; j < y+1; j++) {
            if (i == 0 || j == 0) {
                LCS[i][j] = 0;
//                printf("0 LCS[%d][%d] = %d\n", i, j, LCS[i][j]);
            }
            else if (X[i-1] == Y[j-1]) {
                LCS[i][j] = LCS[i-1][j-1] + 1;
//                printf("1 LCS[%d][%d] = %d\n", i, j, LCS[i][j]);
            }
            else {
                LCS[i][j] = (LCS[i-1][j] > LCS[i][j-1]) ? LCS[i-1][j] : LCS[i][j-1]; 
//                printf("LCS[%d][%d] = %d\n", i, j, LCS[i][j]);
            }
        }
    }

    return LCS[x][y]; 
}

int main() {
    int q;
    int x;
    int y;

    cin >> q;

    for (int i = 0; i < q; i++) {
        scanf("%s", X);
        x = strlen(X);
        scanf("%s", Y);
        y = strlen(Y);
        cout << longest(x, y) << endl;
    }
        
    return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i=0; i<(int)(n); i++)
#define all(v) v.begin(), v.end()
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
const ll MOD = 1000000007;
const ll INF = 9999999999;
const int INFI = 2147483647;
template<class T> inline bool chmin(T& a, T b){if (a>b){a = b; return true;}return false;}
template<class T> inline bool chmax(T& a, T b){if (a<b){a = b; return true;}return false;}
template<class T> inline T powerM(T a,T b){if (b==0) return 1;
  T tmp = powerM(a,b/2); if (b%2==0) return tmp*tmp%MOD; else return tmp*tmp%MOD*a%MOD; }

int main() {
  int q; cin >>q;
  vector<vector<int>> dp;
  rep(query, q){
    string s,t; cin >>s >>t;
    int n = s.size(), m = t.size();
    dp.assign(n+1, vector<int>(m+1, 0));
    // dp[i][j]...sのi文字目まで、tのj文字目までの最長共通部分列の長さ
    for (int i=0; i<n; i++){
      for (int j=0; j<m; j++){
        if (s.at(i) == t.at(j)) chmax(dp[i+1][j+1], dp[i][j] + 1);
        chmax(dp[i+1][j+1], dp[i][j+1]);
        chmax(dp[i+1][j+1], dp[i+1][j]);
      }
    }
    cout <<dp[n][m] <<endl;
  }
}

C++: #include <iostream>
#include <list>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <algorithm>
#include <cmath>
#include <string>
using namespace std;
typedef long long lli;
typedef vector<lli> vll;
typedef vector<bool> vbl;
typedef vector<vector<lli> > mat;
typedef vector<vector<bool> > matb;
typedef vector<string> vst;
typedef pair<lli,lli> pll;
typedef pair<double,double> pdd;

lli n;
string x;
string y;

mat dp;

int main(){
    cin >> n;
    for(lli i = 0;i < n;i++){
        cin >> x >> y;
        dp = mat(x.size()+2,vll(y.size()+2));
        for(lli i = 0;i <= x.size();i++){
            for(lli j = 0;j <= y.size();j++){
                dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
                dp[i][j+1] = max(dp[i][j+1],dp[i][j]);
                if(x[i] == y[j]) dp[i+1][j+1] = max(dp[i+1][j+1],dp[i][j]+1);
            }
        }
        cout << dp[x.size()][y.size()] << endl;
    }
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
static const int N=1001;
int lcs(string& X,string& Y){
  int c[N][N] = {};
  int m=X.size();
  int n=Y.size();

  int max1=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]);
      }
      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<vector>
#include<string>
#include<algorithm>

using namespace std;

string s, t;

int main() {
	int n;
	cin >> n;
	while (n--) {
		//dp[i][j] := s???i??????????????§???t???j??????????????§?????£?????¨??????LCS
		vector<vector<int>> dp(2000, vector<int>(2000));
		cin >> s >> t;
		dp[0][0] = (s[0] == t[0]);
		for (int i = 1; i < s.size(); i++)dp[i][0] = (bool)(dp[i-1][0] + (s[i] == t[0]));
		for (int j = 1; j < t.size(); j++)dp[0][j] = (bool)(dp[0][j-1] + (s[0] == t[j]));
		
		for (int i = 1; i < s.size(); i++) {
			for (int j = 1; j < t.size(); j++) {
				if (s[i] == t[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[s.size() - 1][t.size() - 1] << endl;
	}
}

C++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
using namespace std;
const int num = 1001;
int lg[num + 1][num + 1];
int main() {
	int w;
	string s, t;
	cin >> w;
	for (int i = 0; i < w; i++) {
		cin >> s;
		cin >> t;
		int n = s.size();
		int m = t.size();
		for (int i = 0; i < n; i++) lg[i][0] = 0;
		for (int i = 0; i < m; i++) lg[0][i] = 0;
		for (int i = 0; i < n; i++)
			for (int j = 0; j < m; j++) {
				if (s[i] == t[j]) lg[i + 1][j + 1] = lg[i][j] + 1;
				else lg[i + 1][j + 1] = max(lg[i][j + 1], lg[i + 1][j]);
			}
		cout << lg[n][m] << endl;
	}
	return 0;
	/*int n, m;
	char s[num], t[num];
	cin >> n >> m;
	for (int i = 0; i < n; i++) cin >> s[i];
	for (int i = 0; i < m; i++) cin >> t[i];
	for (int i = 0; i < n; i++) lg[i][0] = 0;
	for (int i = 0; i < m; i++) lg[0][i] = 0;
	for (int i = 0; i < n; i++)
		for (int j = 0; j < m; j++) {
			if (s[i] == t[j]) lg[i + 1][j + 1] = lg[i][j] + 1;
			else lg[i + 1][j + 1] = max(lg[i][j + 1], lg[i + 1][j]);
		}
	cout << lg[n][m] << endl;
	return 0;*/
}