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;

int	lcs(const string &X, const string &Y)
{
	int	len_X = X.size(), len_Y = Y.size();
	int	len_lcs[1001][1001] = {};
	for (int i = 0; i < len_X; ++i) {
		for (int j = 0; j < len_Y; ++j) {
			int	prev_X = len_lcs[i][j + 1];
			int	prev_Y = len_lcs[i + 1][j];
			int	prev = max(prev_X, prev_Y);	
			if (X.at(i) == Y.at(j)) {
				len_lcs[i + 1][j + 1] = max(len_lcs[i][j] + 1, prev);
			} else {
				len_lcs[i + 1][j + 1] = prev;
			}
		}
	}
	return len_lcs[len_X][len_Y];
}

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

C++: #include<iostream>
using namespace std;
/*int lcs(string a,string b)
{
    if(a.length()<=0||b.length()<=0)
    {
        return 0;
    }
    else if(a[a.length()-1]==b[b.length()-1])
    {
        return 1+lcs(a.substr(0,a.length()-1),b.substr(0,b.length()-1));
    }
    else
    {
        return max(lcs(a.substr(0,a.length()),b.substr(0,b.length()-1)),lcs(a.substr(0,a.length()-1),b.substr(0,b.length())));
    }
};*/
int main()
{
    int num;
    cin>>num;
    for(int i=0;i<num;i++)
    {
        int lcs[1001][1001]={};
        string a,b;
        cin>>a>>b;
        //cout<<lcs(a,b)<<endl;
        for(int i=0;i<a.length()+1;i++)
        {
            for(int j=0;j<b.length()+1;j++)
            {
                if(i==0||j==0)
                {
                    lcs[i][j]=0;
                }
                else if(a[i]==b[j])
                {
                    lcs[i][j]=lcs[i-1][j-1]+1;
                }
                else
                {
                    lcs[i][j]=max(lcs[i][j-1],lcs[i-1][j]);
                }
            }
        }
        cout<<lcs[a.length()][b.length()]<<endl;
    }
}

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

int dp[1002][1002] = { 0 };

int main() {
	int q;
	cin >> q;
	for (int i = 0; i < q; ++i) {
		string x, y;
		int cnt = 0;
		cin >> x >> y;
		memset(dp, 0, sizeof(dp));

		for (int j = 1; j <= x.size(); ++j) {
			for (int j2 = 1; j2 <= y.size(); ++j2) {
				if (x[j - 1] == y[j2 - 1]) {
					dp[j][j2] = max(dp[j][j2 - 1], dp[j - 1][j2 - 1] + 1);
				}
				else {
					dp[j][j2] = max(dp[j][j2 - 1], dp[j - 1][j2]);
				}
			}
		}
		cout << dp[x.size()][y.size()] << endl;
	}

	return 0;
}

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

int main(){
        int q;
        scanf("%d",&q);
        while(q--){
                string str1,str2;
                cin >> str1 >> str2;
                vector<vector<int>> dp(str1.size()+1,vector<int>(str2.size()+1,0));
                for(int i = 0; i < str1.size(); i++){
                        for(int j = 0; j < str2.size(); j++){
                                if(str1[i] == str2[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[str1.size()][str2.size()] << endl;
        }
        return 0;
}

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

using std::cin;
using std::cout;
using std::cerr;
using std::endl;

// 最長共通部分列 ... len(s) == m, len(t) == n とすると, O(mn)
int lcs(std::string& s, std::string& t) {
  std::vector<std::vector<int> > dp(s.size() + 1, std::vector<int>(t.size() + 1, 0));

  for (int i = 1; i <= s.size(); ++i) {
    for (int j = 1; j <= t.size(); ++j) {
      if (s[i - 1] == t[j - 1]) {
        dp[i][j] = dp[i - 1][j - 1] + 1;
      }
      else if (dp[i - 1][j] >= dp[i][j - 1]) {
        dp[i][j] = dp[i - 1][j];
      }
      else {
        dp[i][j] = dp[i][j - 1];
      }
    }
  }

  return dp[s.size()][t.size()];
}

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

  return 0;
}

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

int main()
{
    int Q;
    cin >> Q;
    for (int i = 0; i < Q; i++) {
        string X, Y;
        cin >> X >> Y;
        int x, y;
        x = X.size();
        y = Y.size();
        // dp[i][j] := X[i], Y[j] まで見た時のLCS
        int dp[x + 5][y + 5];
        for (int i = 0; i < x + 5; i++) {
            for (int j = 0; j < y + 5; j++) {
                dp[i][j] = 0;
            }
        }
        for (int i = 0; i < x; i++) {
            for (int j = 0; j < y; j++) {
                if (X[i] == Y[j]) {
                    dp[i + 1][j + 1] = max({ dp[i][j] + 1, dp[i + 1][j], dp[i][j + 1] });
                } else {
                    dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
                }
            }
        }
        printf("%d\n", dp[x][y]);
    }
}

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

int main() {
  std::ios::sync_with_stdio(false);
  cout.tie(0);
  cin.tie(0);
  int N;
  cin>>N;
  string S1,S2;
  for (int k=0; k<N; k++) {
    cin>>S1>>S2;
    int m=S1.length();
    int n=S2.length();
    S1=' '+S1;
    S2=' '+S2;
    int lcs[1001][1001];
    for (int i=1; i<=m; i++) {
      lcs[i][0]=0;
    }
    for (int j=1; j<=n; j++) {
      lcs[0][j]=0;
    }
    int maxl=0;
    for (int i=1; i<=m; i++) {
      for (int j=1; j<=n; j++) {
        if (S1[i]==S2[j]) {
          lcs[i][j]=lcs[i-1][j-1]+1;
        }
        else {
          lcs[i][j]=max(lcs[i-1][j],lcs[i][j-1]);
        }
        maxl=max(maxl,lcs[i][j]);
      }
    }
    cout<<maxl<<endl;
  }
  return 0;
}