Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func lcs(a, b string) int {
	lenA := len(a)
	lenB := len(b)
	dp := make([][]int, lenA+1)
	for i := range dp {
		dp[i] = make([]int, lenB+1)
	}

	for i := 1; i <= lenA; i++ {
		for j := 1; j <= lenB; j++ {
			if a[i-1] == b[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = max(dp[i][j-1], dp[i-1][j])
			}
		}
	}
	return dp[lenA][lenB]
}

func main() {
	n := scanInt()
	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		a := scanString()
		b := scanString()
		fmt.Fprintln(w, lcs(a, b))
	}
	w.Flush()
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vs = vector<string>;
using msi = map<string, int>;
using mii = map<int, int>;
using psi = pair<string, int>;
using pii = pair<int, int>;
using vlai = valarray<int>;
#define rep(i,n) for(int i=0;i<n;i++)
#define range(i,s,n) for(int i=s;i<n;i++)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define fs first
#define sc second
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define INF 1E9
#define EPS 1E-9
#define MOD (1E9+7)
#define PI 3.1415926535897932384626433832795

std::ostream &operator<<(std::ostream &out, const vector<int> &tgt)
{
	string s;
	for (int i = 0; i<tgt.size(); i++) {
		s += (to_string(tgt[i]) + ((i != tgt.size() - 1) ? " " : ""));
	}
	out << s;
	return out;
}

void solve(string a, string b) {
	vvi dp(a.size()+1, vi(b.size()+1,0));
	for (int i = 1; i < dp.size(); i++) {
		for (int j = 1; j < dp[0].size(); j++) {
			if (a[i - 1] == b[j - 1]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			}
			else {
				dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
			}
		}
	}
	cout << dp[a.size()][b.size()] << endl;
}

int main() {
	int n;
	cin >> n;
	string a, b;
	rep(i, n) {
		cin >> a >> b;
		solve(a, b);
	}
}

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

int main () {
    int N;
    cin >> N;
    vector<string> S(N), T(N);
    for (int i = 0; i < N; i++)
        cin >> S[i] >> T[i];

    for (int i = 0; i < N; i++) {
        int dp[1001][1001] = {};
        string s = S[i], t = T[i];
        int n = s.size(), m = t.size();
        for (int j = 0; j < n; j++) {
            for (int k = 0; k < m; k++) {
                if (s[j] == t[k]) {
                    dp[j + 1][k + 1] = dp[j][k] + 1;
                } else {
                    dp[j + 1][k + 1] = max(dp[j + 1][k], dp[j][k + 1]);
                }
            }
        }
        cout << dp[n][m] << endl;
    }
    return 0;
}

C++: #include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
int main(){
  char str1[1000],str2[1000];
  int LCS[1000][1000]={0};
  int length1,length2;
  int n;
  std::ios::sync_with_stdio(false);
  scanf("%d",&n);
  for(int s=1;s<=n;s++){
   while(cin>>str1>>str2){
     length1=strlen(str1);
     length2=strlen(str2);
     for(int i=0;i<=length1-1;i++){
       LCS[i][0]=0;
     }
     for(int j=0;j<=length2-1;j++){
       LCS[0][j]=0;
     }
     for(int i=1;i<=length1;i++){
       for(int j=1;j<=length2;j++){
         if(str1[i-1]==str2[j-1]) {
           LCS[i][j]=LCS[i-1][j-1]+1;
         }
         else LCS[i][j]=max(LCS[i-1][j],LCS[i][j-1]);
       }
     }
     printf("%d\n",LCS[length1][length2]);
   }
 }
   return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define INF 100000000000
const int MOD = 1000000009;

//マクロ
#define FOR(i, a, b) for(int i = (a); i < (b), i++)
#define REP(i, n) FOR(i, 0, n);
#define ALL(a) (a).begin(),(a).end()

// 最長共通部分列問題
// 入力
// S T

// dp[i + 1][j + 1] := Sのi文字目までと、Tのj文字目までのLCSの長さ
// 計算量 O(|S||T|)

int main(){

    //入力
    int n; cin >> n;
    for(int roop = 0; roop < n; roop++){
        string S, T; cin >> S >> T;
        vector<vector<int> > dp(S.size() + 1, vector<int> (T.size() + 1, INF));

        //dp初期条件
        dp[0][0] = 0;

        //dp
        for(int i = 0; i < S.size(); i++){
            for(int j = 0; j < T.size(); j++){
                if(S[i] == T[j]) dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j]);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i + 1][j]);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j + 1]);
            }
        }

        cout << dp[S.size()][T.size()];
        return 0;
    }
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <map>
#include <stack>
#include <queue>
#include <set>
#include <cstring>

using namespace std;
// ascending order
#define vsort(v) sort(v.begin(), v.end())
// descending order
#define vsort_r(v) sort(v.begin(), v.end(), greater<int>())
#define vunique(v) v.erase(unique(v.begin(), v.end()), v.end())
#define mp make_pair
#define ts(x) to_string(x)
#define rep(i, a, b) for(int i = (int)a; i < (int)b; i++)
#define repm(i, a, b) for(int i = (int)a; i > (int)b; i--)
#define bit(a) bitset<8>(a)
#define des_priority_queue priority_queue<int, vector<int>, greater<int> >
typedef long long ll;
typedef pair<int, int> P;
const ll INF = 1e18;

#define MAX_V 1000000

int solve(string x, string y) {
  int dp[x.size() + 1][y.size() + 1];
  memset(dp, 0, sizeof(dp));
  rep(i, 0, x.size()) {
    rep(j, 0, y.size()) {
      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[x.size()][y.size()];
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

  int q;
  cin >> q;
  vector<int> rsl;
  rep(i, 0, q) {
    string x, y;
    cin >> x >> y;
    rsl.push_back(solve(x, y));
  }
  rep(i, 0, rsl.size()) cout << rsl[i] << endl;
}

C++: #include<iostream>
#include<vector>b
using namespace std;
int main()
{
	int kurikaeshi;
	vector<int> answer;
	cin >> kurikaeshi;
	for (int variable = 0;variable < kurikaeshi;++variable) {
		char X[1024], Y[1024];
		int LX = 0, LY = 0;
		vector<vector<int>> L;
		cin >> X >> Y;
		for (int i = 0;X[i] != 0;++i) LX += 1;
		for (int j = 0;Y[j] != 0;++j) LY += 1;
		L.resize(LX+1);
		for (int k = 0;k < LX + 1;++k) L[k].resize(LY+1);
		for (int i = 0;i<LX+1;++i) {
			for (int j = 0;j<LY+1;++j) {
				if (i == 0 || j == 0) {
					L[i][j] = 0;
				}
				else if (X[i-1] == Y[j-1]) {
					L[i][j] = L[i][j-1] + 1;
				}
				else {
					L[i][j] = L[i-1][j] > L[i][j-1] ? L[i-1][j] : L[i][j-1];
				}
			}
		}
		answer.push_back(L[LX][LY]);
	}
	for (int variable = 0;variable < kurikaeshi;++variable) {
		cout << answer[variable] << endl;
	}
}

C++: #include<bits/stdc++.h>

using namespace std;
using ll = long long;


int main()
{
    int q;
    cin >> q;
    vector<int> ans;

    while(q--) {

        string s, t;
        cin >> s >> t;
        int n = s.size(), m = t.size();
        vector<vector<int>> dp(n + 1, vector<int>(m + 1)); //dp[i][j] := sのi文字目, tのj文字目まで見た時の最長
        
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < m; j++) {

                if(s[i] == t[j]) {
                    dp[i + 1][j + 1] = max({dp[i + 1][j], dp[i][j + 1], dp[i][j] + 1});
                }else{
                    dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
                }
            }
        }
        ans.push_back(dp[n][m]);
    }
    for(auto i : ans) {
        cout << i << endl;
    }

}