Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	resolve()
}

func resolve() {
	n := scanInt(sc)
	results := []int{}
	for i := 0; i < n; i++ {
		results = append(results, resolveInstance())
	}
	for _, v := range results {
		fmt.Println(v)
	}
	return
}

func resolveInstance() int {
	x, y := scanString(sc), scanString(sc)
	lx, ly := len(x), len(y)
	dp := make([][]int, lx+1)
	dp[0] = make([]int, ly+1)
	for i := 1; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
		dp[i][0] = dp[i-1][0]
		for j := 1; j <= ly; j++ {
			dp[i][j] = dp[i-1][j]
			if dp[i][j] < dp[i][j-1] {
				dp[i][j] = dp[i][j-1]
			}
			if x[i-1] == y[j-1] {
				cL := dp[i-1][j-1] + 1
				if dp[i][j] < cL {
					dp[i][j] = cL
				}
			}
		}
	}
	return dp[lx][ly]
}

const (
	remove = 0 + iota
	match
)

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

#define rep(i,x,y) for(int i=(x);i<(y);++i)
#define mp(a,b) make_pair((a),(b))
#define debug(x) #x << "=" << (x)
 
#ifdef DEBUG
#define _GLIBCXX_DEBUG
#define dump(x) std::cerr << debug(x) << " (L:" << __LINE__ << ")" << std::endl
#else
#define dump(x)
#endif

typedef long long int ll;
typedef pair<int,int> pii;
//template<typename T> using vec=std::vector<T>;

const int INF=1<<30;
const long long int INFLL=1LL<<58;
const double EPS=1e-9;
const int dx[]={1,0,-1,0},dy[]={0,1,0,-1};

template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec){
	os << "[";
	for (const auto &v : vec) {
		os << v << ",";
	}
	os << "]";
	return os;
}

void solve_(){
     string a,b;
    cin >> a >> b;
    
    static int dp[1000][1000];
    fill_n((int*)dp,1000*1000,0);
    
    rep(i,0,a.size()){
        rep(j,0,b.size()){
            if(i!=0) dp[i][j]=dp[i-1][j];
            if(j!=0) dp[i][j]=max(dp[i][j],dp[i][j-1]);
            
            if(a[i]!=b[j]) continue;
            
            if(i==0&&j==0) dp[0][0]=1;
            else if(i==0) dp[0][j]=1;
            else if(j==0) dp[i][0]=1;
            else dp[i][j]=max(dp[i][j],dp[i-1][j-1]+1);
        }
    }
    
    cout << dp[a.size()-1][b.size()-1] << endl;
}

void solve(){
    int n;
    cin >> n;
    rep(i,0,n) solve_();
}

int main(){
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	solve();
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<cstring>
using namespace std;
const int MAX=1005;
int dp[MAX][MAX]={0};
int main(){
	string x,y;
	int q;
	cin>>q;
	while(q--){
		cin>>x>>y;
		memset(dp,0,sizeof(dp));
		x=" "+x;y=" "+y;
		for(int i=1;i<x.length();i++){
			for(int j=1;j<y.length();j++){
				if(x[i]==y[j])dp[i][j]=dp[i-1][j-1]+1;
				else {
					dp[i][j]=max(dp[i][j-1],dp[i-1][j]);
				}
			}
		}
		cout<<dp[x.length()-1][y.length()-1]<<endl;
	}
	return 0;
}

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

int main(){
  int n;
  std::string x,y;
  std::cin>>n;
  int a[1000][1000];
  int b[n];

  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
	a[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  a[j][k]=a[j-1][k-1]+1;
	}else{
	  if(a[j-1][k]>a[j][k-1]){
	    a[j][k]=a[j-1][k];
	  }else{
	    a[j][k]=a[j][k-1];
	  }
	}
      }
    }
    b[i]=a[x.size()-1][y.size()-1];
  }

  for(int i=0;i<n;i++){
  std::cout<<b[i]<<"\n";
  }

  return 0;
}

C++: #include <iostream>
#include <string>
 
int main() {
  std::string str1,str2;
  int n;
  int A[1001][1001];
  std::cin>>n;
  for(int i=0;i<n;i++){
    std::cin>>str1;
    std::cin>>str2;
    for(int j=0;j<1001;j++){
      for(int k=0;k<1001;k++){
	A[j][k]=0;
      }
    }
    for(int j=1;j<=str1.size();j++){
      for(int k=1;k<=str2.size();k++){
	if(str1[j-1]==str2[k-1]){
	  A[j][k]=A[j-1][k-1]+1;
	}else{
	  if(A[j-1][k]>A[j][k-1]){
	    A[j][k]=A[j-1][k];
	  }else{
	    A[j][k]=A[j][k-1];
	  }
	}
      }
    }
    std::cout<<A[str1.size()][str2.size()]<<"\n";
  }
  return 0;
 
}

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

int dp[1001][1001] = {{0}};

int LCS(string X, string Y){
    auto len_x = X.length();
    auto len_y = Y.length();
    for (int i = 0; i != len_x; ++i){
        for (int j = 0; j != len_y; ++j){
            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]);
            }
        }
    }
    return dp[len_x][len_y];
}

int main()
{
    ios::sync_with_stdio(false);
    
    int q = 0;
    cin >> q;
    
    string X;
    string Y;
    while (q--){
        cin >> X;
        cin >> Y;
        cout << LCS(X, Y) << endl;
    }
    return 0;
}

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

#define MAX 1000

int c[MAX + 1][MAX + 1];

int lcs(string X, string Y) {
	for (int i = 0; i <= X.size(); i++)
		c[i][0] = 0;
	for (int j = 0; j <= Y.size(); j++)
		c[0][j] = 0;
	for (int i = 1; i <= X.size(); i++) {
		for (int j = 1; j <= Y.size(); j++) {
			if (X[i - 1] == Y[j - 1]) {
				c[i][j] = c[i - 1][j - 1] + 1;
			} else {
				c[i][j] = max(c[i - 1][j], c[i][j - 1]);
			}
		}
	}
	return c[X.size()][Y.size()];
}

int main() {
	int q;
	cin >> q;
	for (int i = 0; i < q; i++) {
		string X, Y;
		cin >> X >> Y;
		cout << lcs(X, Y) << endl;
	}
	return 0;
}

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

int main(){
    int q;
    cin >> q;

    vector<string> X(q+1), Y(q+1);

    for(int i=0; i<q; i++){
        cin >> X[i] >> Y[i];
    }

    for(int number=0; number<q; number++){//q個のデータセットについて実行する

        int dp[1010][1010] = {0};

        for(int i=0; i<=X[number].size(); i++){
            for(int j=0; j<=Y[number].size(); j++){
                if(X[number][i] == Y[number][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[X[number].size()][Y[number].size()] << endl;
    }
}

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


 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;
}