Go: package main

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

func max(x, y int) int {
	if x < y {
		return y
	} else {
		return x
	}
}

/*********************************************************************
長さmの列X_(m)と長さnの列Y_(n)の最長共通部分列LCSは、
	(1)X[m] == Y[n]ならば、X_(m-1)とY_(n-1)のLCSにX[m]を繋げたもの
	(2)X[m] != Y[n]ならば、X_(m-1)とY_(n)のLCSもしくはX_(m)とY_(n-1)のLCS
	のいずれかのうち長い方

c[m+1][n+1]：c[i][j]にX_(i)とY_(j)のLCSの長さを格納する二次元配列
*********************************************************************/

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		scanner.Scan()
		s1 := scanner.Text()
		scanner.Scan()
		s2 := scanner.Text()
		s1, s2 = s1 + " ", s2 + " "
		c := make([][]int, len(s1))
		for i := range c {
			c[i] = make([]int, len(s2))
		}

		LCS := 0

		for i := 1; i < len(s1); i++ {
			for j := 1; j < len(s2); j++ {
				if s1[i] == s2[j] {
					c[i][j] = c[i-1][j-1] + 1
				} else {
					c[i][j] = max(c[i-1][j], c[i][j-1])
				}
				LCS = max(LCS, c[i][j])
			}
		}
		fmt.Println(LCS)
	}
}

C++: #include <iostream>

using namespace std;

typedef long long signed int ll;

constexpr ll NIL = -20000000000;

string s[2];
int dp[1001][1001];

int lcs(int x,int y) {
    if(x < 0 || y < 0) return 0;
    if(x >= s[0].size() || y >= s[1].size()) return 0;
    if(dp[x][y] == -1) {
        dp[x][y] = max(lcs(x+1,y),dp[x][y]);
        dp[x][y] = max(lcs(x,y+1),dp[x][y]);
        if(s[0][x] == s[1][y]) dp[x][y] = max(lcs(x+1,y+1) + 1,dp[x][y]);
    }
    return dp[x][y];
}

int main() {
    int n;
    cin >> n;
    for(int i = 0;i < n;i++) {
        cin >> s[0] >> s[1];
        int res = -1;
        for(int j = 0;j < 1001 * 1001;j++)(reinterpret_cast<int*>(dp))[j] = -1;
        for(int j = 0;j < 1001 * 1001;j++)res = max(res,(reinterpret_cast<int*>(dp))[j]);
        cout << lcs(0,0) << endl;
    }
}

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

#define MAX 1000

int DP[MAX][MAX];

int main(){
  int n;
  
  std::cin >> n;
  
  for(int t = 0; t < n; t++){
    std::string str1, str2;

    std::cin >> str1;
    std::cin >> str2;
    
    const int one_len = str1.length();
    const int two_len = str2.length();
    
    for(int i = 0; i < one_len; i++){
      for(int j = 0; j < two_len; j++){
	DP[i][j] = 0;
      }
    }

    for(int i = 0; i < one_len; i++){
      for(int j = 0; j < two_len; j++){
	if(i == 0 && j == 0){
	  DP[i][j] = str1[i] == str2[j] ? 1 : 0;
	}else if(i == 0){	
	  DP[i][j] = std::max(DP[i][j-1], str1[i] == str2[j] ? 1 : 0);
	}else if(j == 0){
	  DP[i][j] = std::max(DP[i-1][j], str1[i] == str2[j] ? 1 : 0);
	}else{
	  DP[i][j] = std::max(DP[i-1][j-1] + (str1[i] == str2[j] ? 1 : 0), std::max(DP[i-1][j], DP[i][j-1]));
	}
      }
    }
    
    std::cout << DP[one_len - 1][two_len - 1] << std::endl;
  }
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
static const int N=1000;

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; // X[0]に空白を挿入
    Y = ' ' + Y;
    for (int i=0; i<=m; i++) C[i][0] = 0;
    for (int j=0; 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][j-1], C[i-1][j]);
            }
            maxl = max(maxl, C[i][j]);
        }
    }
    
    return maxl;
}

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 <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin >> n;
    for(int q=0;q<n;q++){
        string x,y;
        cin >>x >> y;
        int dp[1002][1002];
        memset(dp,-1, sizeof(dp));
        dp[0][0] = 0;
        for(int i=0;i<x.size()+1;i++){
            for(int j=0;j<y.size()+1;j++){
                if (i < x.size() && j < y.size() && x[i] == y[j]){
                dp[i+1][j+1] = max(dp[i+1][j+1], dp[i][j] + 1);
                }
                dp[i][j+1] = max(dp[i][j+1],dp[i][j]);
                dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
            }
        }
        cout << dp[x.size()][y.size()] << endl;
    }
}

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

int lcs(std::string x, std::string y) {
	if (x.length() > y.length()) { x.swap(y); }
	int lx = x.length(), ly = y.length();
	std::vector<std::vector<int>> dp(ly, std::vector<int>(lx));

	dp.at(0).at(0) = (int)(x[0] == y[0]);
	for (int i = 1; i < ly; i++) {
		dp.at(i).at(0) = std::max(dp.at(i - 1).at(0), (int)(x[0] == y[i]));
		if (i < lx) { dp.at(0).at(i) = std::max(dp.at(0).at(i - 1), (int)(x[i] == y[0])); }
	}

	for (int i = 1; i < lx; i++) {
		dp.at(i).at(i) = std::max(dp.at(i - 1).at(i), dp.at(i).at(i - 1));
		if (x[i] == y[i]) { dp.at(i).at(i) = dp.at(i - 1).at(i - 1) + 1; }
		
		for (int t = i + 1; t < ly; t++) {
			if (x[i] == y[t]) { dp.at(t).at(i) = dp.at(t - 1).at(i - 1) + 1; } 
			else { dp.at(t).at(i) = std::max(dp.at(t).at(i - 1), dp.at(t - 1).at(i)); }

			if (t < lx) {
				if (x[t] == y[i]) { dp.at(i).at(t) = dp.at(i - 1).at(t - 1) + 1; } 
				else { dp.at(i).at(t) = std::max(dp.at(i).at(t - 1), dp.at(i - 1).at(t)); }

			}
		}
	}
	return dp.at(ly-1).at(lx-1);
}

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

C++: #include <bits/stdc++.h>
using namespace std;
string s1,s2;
// 公共
int dp[1005][1005];
void solve(){
	memset(dp,0,sizeof(dp));
	for(int i=1;i<s1.length();i++)
		for(int j=1;j<=s2.length();j++)
			dp[i][j]=(s1[i]==s2[j]?dp[i-1][j-1]+1:max(dp[i-1][j],dp[i][j-1]));
	cout<<dp[s1.length()-1][s2.length()-1]<<endl;
}
int main(){
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//	freopen("a.txt","r",stdin);
	int T;cin>>T;
	while(T--){
		cin>>s1>>s2;
		s1=" "+s1;
		s2=" "+s2;
		solve();		
	}
	return 0;
}

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


int main(){
  string X, Y;
  int q;
  cin >> q;
  for(int i = 0; i < q; i++){
    cin >> X >> Y;
    vector<vector<int> > dp(X.size(), vector<int>(Y.size(), 0));
    for(int i = 0; i < X.size(); i++){
      for(int j = 0; j < Y.size(); j++){
        if(X[i] == Y[j]){
          if(i == 0 || j == 0)dp[i][j] = 1;
          else dp[i][j] = dp[i - 1][j - 1] + 1;
        }else {
          if(i == 0 && j == 0)dp[i][j] = 0;
          else if(i == 0 && j != 0)dp[i][j] = dp[i][j - 1];
          else if(i != 0 && j == 0)dp[i][j] = dp[i - 1][j];
          else dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
        }
      }
    }
    cout << dp[X.size() - 1][Y.size() - 1] << endl;
  }
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
static const int N = 1000;

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;
  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]);
      maxl = max(maxl, c[i][j]);
    }

  return maxl;
}

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;
}