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, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;
int dp[1005][1005];

int main() {
  int n;
  cin>>n;
  rep(_,n){
    string s,t;
    cin>>s>>t;
    int sn=s.size(),tn=t.size();
    rep(i,sn) rep(j,tn){
      if(s[i]==t[j]) dp[i+1][j+1]=dp[i][j]+1;
      else dp[i+1][j+1]=max(dp[i+1][j],dp[i][j+1]);
    }
    cout<<dp[sn][tn]<<endl;
  }
  return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int i = 0;i<n;i++)
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0;}

int main() {
    int q; cin >> q;
    rep(i,q) {
        string s,t;
        cin >> s >> t;
        int dp[1010][1010];
        int n = s.size();
        int m = t.size();
        rep(i,m+1) dp[0][m] = 0;
        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][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]);
                }
            }
        }
        cout << dp[n][m] << endl;
    }
}

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

using namespace std;

int LCS(string X, string Y){
    int m = X.length();
    int n = Y.length();
    int C[m+1][n+1];
    int ans = 0;
    
    for(int i = 0; i <= m; i++) C[i][0] = 0;
    for(int i = 1; i <= n; i++) C[0][i] = 0;
    for(int i = 1; i <= m; i++){
        for(int j = 1; j <= n; j++){
            
            if(X[i-1] == Y[j-1]){
                C[i][j] = C[i-1][j-1] + 1;
            } 
            else if(C[i-1][j]> C[i][j -1]) {
                C[i][j] = C[i-1][j];
            }
            else C[i][j] = C[i][j-1];
            
            if(ans < C[i][j]) ans = C[i][j];
        }
    }
    
    return ans;
    
}
int main(){
    string x,y;
    int n;
    cin >> n;
    for(int i = 0; i < n; i ++){
        cin >> x >> y;
        cout << LCS(x,y) << endl;
    }
    return 0;
}

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

static const long N = 1000;

long lcs(string X, string Y){
	long c[N + 1][N + 1];
	long m = X.size();
	long n = Y.size();
	long maxl = 0;
	X = ' ' + X;
	Y = ' ' + Y;
	for (long i = 1; i <= m; i++) c[i][0] = 0;
	for (long j = 1; j <= n; j++) c[0][j] = 0;

	for (long i = 1; i <= m; i++){
		for (long 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;
	long n; cin >> n;
	for (long i = 0; i < n; i++){
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}

C++: #include<math.h>
#include<limits.h>
#include<iostream>
#include<string>
#include<vector>
#include<stdio.h>
#include<sstream>
#include<list>
#include<queue>
#include<algorithm>
#include<functional>
#include<map>
#include<set>
#include<utility>
#include<initializer_list>
#include<tuple>
#include<regex>
using namespace std;
#define ull unsigned long long
#define ll long long
#define rep(i, n) for(int i=0;i<(int)(n);i++)
#define all(t) t.begin(), t.end()
bool isSubstring(string substr, string t) {
	int n = substr.length();
	int seek = 0;
	rep(i, n) {
		bool ex = 0;
		for (int j = seek; j < t.length(); j++) {
			if (substr[i] == t[j]) {
				ex = 1;
				seek = j + 1;
				break;
			}
		}
		if (ex) {
			continue;
		}
		else {
			return false;
		}
	}
	return true;

}

int LongestCommonSubstring(string s, string t) {
	vector<int>dp(s.length(), 0);
	int n = s.length();
	string lcs = "";
	if (isSubstring(s.substr(n - 1, n), t)) {

		dp[n - 1] = 1;
		lcs = s[n - 1];
	}
	for (int i = n - 2; i >= 0; i--) {
		//string substr = s.substr(i, n);
		string substr = s[i] + lcs;
		int issubst = isSubstring(substr, t);
		if (issubst) lcs = substr;
		dp[i] = dp[i + 1] + issubst;
	}
	return dp[0];
}
int main() {
	//cout << isSubstring("abc", "abcde") << endl;
	//cout << isSubstring("bd", "abcde") << endl;
	//cout << isSubstring("db", "abcde") << endl;

	//cout << LongestCommonSubstring("bacd", "becd") << endl;
	//cout << LongestCommonSubstring("abcd", "becd") << endl;
	int q;
	cin >> q;
	vector<string> s(q);
	vector<string> t(q);
	rep(i, q) {
		cin >> s[i] >> t[i];
	}
	rep(i, q) {
		cout << LongestCommonSubstring(s[i], t[i]) << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <cstring>
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;
}

C++: #include<iostream>
#include<string.h>
#include<algorithm>

#define MAX 100

using namespace std;

int lcs(string s1, string s2) {
    int C[MAX+1][MAX+1];
    int m = s1.size();
    int n = s2.size();
    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 (s1[i-1] == s2[j-1]) {
                C[i][j] = C[i-1][j-1] + 1;
            }
            else {
                C[i][j] = max(C[i][j-1], C[i-1][j]);
            }
        }
    }

    return C[m][n];
}

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        string s1, s2;
        cin >> s1 >> s2;
        cout << lcs(s1, s2) << endl;
    }
    return 0;
}