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 <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;
}

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

using namespace std;

int maxa[1000];
int main(){
  int n;
  int k;
  int count;
  cin>>n;
  char X[1001];
  char Y[1001];
  for(int i=0;i<n;i++){
    cin>>X;
    cin>>Y;
    k=0;
    for(int a=0;X[a]!='\0';a++){
    count=0;
      for(int s=a;X[s]!='\0';s++){
	for(int j=k;Y[j]!='\0';j++){
	  if(X[s]==Y[j]){
	    count++;
	    k=j;
	    break;
	  }
	}
      }
      if(maxa[i]<count)maxa[i]=count;
    }
  }
  for(int i=0;i<n;i++){
    cout<<maxa[i]<<endl;
  }
  
  return 0;
}

C++: #define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

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

int main() {
  int q;
  cin >> q;
  rep(k, q) {
    string x, y;
    cin >> x >> y;
    int m = x.size();
    int n = y.size();
    vector<vector<int> > dp(m + 1, vector<int>(n + 1, 0));
    rep(i, m) {
      rep(j, n) {
        if (x[i] == y[j]) {
          dp[i + 1][j + 1] = dp[i][j] + 1;
        } else {
          dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j]);
        }
      }
    }
    cout << dp[m][n] << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <cstring>
#include <math.h>
#include <algorithm>
#include <vector>
#include <string>
#include <stdlib.h>
#include <queue>
#include <stack>
#include <utility>
#include <fstream>
#include <random>
#include <map>
#include <unordered_map>
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,a,b) for(int i=a;i<b;i++)
#define ll long long
#define INF 1000000001
#define mod 1000000007
#define p pair<int,int>
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
using namespace std;
int POW(int x,int y){return int(pow(double(x),double(y)));}



int main(){
	int q;
	cin>>q;
	vector<string> s0(q),t0(q);
	rep(i,q){
		cin>>s0[i]>>t0[i];
	}
	rep(i,q){

	string s,t;
	s=s0[i];
	t=t0[i];
	vector<vector<int>> a(s.size());
	rep(i,s.size()){
		a[i].resize(t.size());
		rep(j,t.size()){
			if(i==0 && j==0){
				if(s[0]==t[0]) a[0][0]=1;
				else a[0][0]=0;
			}else if(j==0){
				if(s[i]==t[0]) a[i][0]=1;
				else a[i][0]=a[i-1][0];
			}else if(i==0){
				if(s[0]==t[j]) a[0][j]=1;
				else a[0][j]=a[0][j-1];
			}else{
				if(s[i]==t[j]) a[i][j]=a[i-1][j-1]+1;
				else a[i][j]=max(a[i][j-1],a[i-1][j]);
			}
		}
	}
	cout<<a[s.size()-1][t.size()-1]<<endl;
	}
}

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

int main(void){
    int q; cin >> q;
    int dp[1001][1001];
    for(int i = 0; i < 1001; i++) dp[0][i] = dp[i][0] = 0;

    for(int i = 0; i < q; i++){
        string a, b; cin >> a >> b;
        int len_a = (int)a.size(), len_b = (int)b.size();
        for(int j = 1; j <= len_a; j++){
            for(int k = 1; k <= len_b; k++){
                if(a[j-1]==b[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 << "(j, k) = " << j << ", " << k << ": dp = " << dp[j][k] << '\n';
            }
        }

        cout << dp[len_a][len_b] << '\n';
    }

    return 0;
}