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++: #define _USE_MATH_DEFINES

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <list>

long long int INF = 1e18;
using namespace std;

typedef pair<long long int, long long int> P;

long long int DP[1001][1001] = {};

int main(){
	
	int n;
	cin >> n;
	
	for(int loop = 0; loop < n; loop++){
		
		string str1, str2;
		cin >> str1 >> str2;
		
		for(int i = 1; i <= str1.size(); i++){
			for(int j = 1; j <= str2.size(); j++){
				if(str1[i - 1] == str2[j - 1]){
					DP[i][j] = max(max(DP[i - 1][j - 1] + 1, DP[i - 1][j]), DP[i][j - 1]);
				}else{
					DP[i][j] = max(DP[i - 1][j], DP[i][j - 1]);
				}
			}
		}
		
		cout << DP[str1.size()][str2.size()] << endl;
	}
	return 0;
}

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

using namespace std;


long long L[1010][1010] {0};
int main(){
  int Q;
  cin >> Q;
  for(int i = 0; i < Q; i++){
    string X, Y;
    cin >> X >> Y;
    int xlen = X.length();
    int ylen = Y.length();
    for(int i = 1; i<= xlen; i++){
      for(int k = 1; k <= ylen; k++){
	if(X[i-1] == Y[k-1]){
	  L[i][k] = 1 + L[i-1][k-1];
	}else{
	  L[i][k] = max(L[i][k-1], L[i-1][k]);
	}
      }
    }

    cout << L[xlen][ylen] << endl;
  }

}

C++: #include <iostream>
#include <string>
using namespace	std;
int main(){

  int n;
  string s1,s2;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>s1>>s2;
    int dp[1001][1001]={};
    for(int j=1;j<=s2.size();j++){
      for(int k=1;k<=s1.size();k++){
        if(s1[k-1]==s2[j-1]) dp[j][k]=dp[j-1][k-1]+1;
        else dp[j][k]=max(dp[j-1][k],dp[j][k-1]);
      }
    }
    cout<<dp[s2.size()][s1.size()]<<endl;
  }
  return 0;

}

C++: #include <bits/stdc++.h>
using namespace std;
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define vv(type, c, m, n, i) vector<vector<type>> c(m, vector<type>(n, i));
#define rep(i,a,n) for(int i=(a), i##_len=(n); i<i##_len; ++i)
#define rrep(i,a,n) for(int i=(a), i##_len=(n); i>i##_len; --i)
#define len(x) ((int)(x).size())
#define mp make_pair
#define eb emplace_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long long> vll;
typedef vector<string> vs;
typedef vector<bool> vb;
constexpr int MAX = 1005;
int main() {
	int n; cin >> n;
	vv(int, dp, MAX, MAX, 0);
	string X, Y;
	rep(i, 0, n) {
		cin >> X >> Y;
		int len_X = len(X);
		int len_Y = len(Y);
		rep(i, 0, len_X) {
			rep(j, 0, len_Y) {
				dp[i + 1][j + 1] = (X[i] == Y[j] ? dp[i][j] + 1 : max(dp[i][j + 1], dp[i + 1][j]));
			}
		}
		P(dp[len_X][len_Y]);
	}
	return 0;
}

C++: #include <iostream>
//#include <iomanip>
#include <string>
#include <vector>
#include <algorithm>
//#include <utility>
//#include <set>
//#include <map>
//#include <queue>
//#include <deque>
//#include <bitset>
//#include <math.h>
using namespace std ;
using ll = long long ;
//using ld = long double ;
using vll = vector<ll> ;
using vvll = vector<vll> ;
//using vc = vector<char> ;
//using vvc = vector<vc> ;
//using vb = vector<bool> ;
//using vvb = vector<vb> ;
//using pll = pair<ll,ll> ;
//#define all(v) v.begin(),v.end()
//ll mod = 998244353 ;
//long double pie = acos(-1) ;
//ll INF = 1000000000000 ;

//void yorn(bool a){if(a) cout << "Yes" << endl ; else cout << "No" << endl ;}
//void YorN(bool a){if(a) cout << "YES" << endl ; else cout << "NO" << endl ;}
//ll gcd(long long a,long long b){if(b==0) return a ; return gcd(b,a%b) ;}
//ll lcm(long long a,long long b){return a/gcd(a,b)*b ;}
//ll sa(long long a,long long b){if(a>b) return a-b ; return b-a ;}
//void fix_cout(){cout << fixed << setprecision(20) ;}
//ld dis(ll a,ll b,ll c,ll d){return sqrt((a-c)*(a-c)+(b-d)*(b-d)) ;}

void chmax(ll &a,ll b){a = max(a,b) ;}

int main(){
	ll q ; cin >> q ;
	for(int tt=0;tt<q;tt++){
		string s,t ;
		cin >> s >> t ;
		vvll dp(s.size()+1,vll(t.size()+1,0)) ;
		for(int i=1;i<=s.size();i++){
			for(int j=1;j<=t.size();j++){
				chmax(dp.at(i).at(j),dp.at(i-1).at(j)) ;
				chmax(dp.at(i).at(j),dp.at(i).at(j-1)) ;
				if(s.at(i-1)==t.at(j-1)) chmax(dp.at(i).at(j),dp.at(i-1).at(j-1)+1) ;
			}
		}
		cout << dp.at(s.size()).at(t.size()) << endl ;
	}
}

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

using namespace std;

int solve(string s1, string s2){
    int L[s1.size()][s2.size()];
    for(int i=0;i<s1.size();i++){
        for(int j=0;j<s2.size();j++){
            if(i==0 || j==0){
                if(s1[i] == s2[j])
                    L[i][j] = 1;
                else
                    L[i][j]=0;
            }
            else if(s1[i] == s2[j]){
                L[i][j] = 1 + L[i-1][j-1];
            }
            else{
                L[i][j] = max(L[i][j-1],L[i-1][j]);
            }
        }
    }
    return L[s1.size()-1][s2.size()-1];
}

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

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

#define PB push_back
#define ALL(a)  (a).begin(),(a).end()
#define DWN(a)  (a).begin(),(a).end(), greater<int>()
#define rep(i, m) for (int i = 0; i < m; i++)
#define REP(i, n, m) for (int i = n; i < m; i++)

#define mod 1000000007

using namespace std;

int q;
string s, t;
int dp[151][151];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cin >> q;
	rep(k, q) {
		cin >> s >> t;
		rep(i, q) rep(j, q) dp[i][j] = 0;
		rep(i, s.size()) {
			rep(j, t.size()) {
				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[s.size()][t.size()] << "\n";
	}
	return 0;
}

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

int main()
{
	int q, t1, t2;
	string s1, s2;
	const int maxS = 1000;
	int m[maxS][maxS];

	cin >> q;

	for (int i = 0; i < q; i++) {

		for (int i = 0; i < maxS; i++)
			for (int j = 0; j < maxS; j++)
				m[i][j] = 0;

		cin >> s1 >> s2;

		t1 = s1.size() - 1;
		t2 = s2.size() - 1;

		if (s1[0] == s2[0])
			m[0][0] = 1;

		for (int i = 0; i < t1; i++) {
			int f = 0;
			if (s1[i + 1] == s2[0])
				f = 1;
			m[i + 1][0] = max(m[i][0], f);
		}

		for (int j = 0; j < t2; j++) {
			int f = 0;
			if (s2[j + 1] == s1[0])
				f = 1;
			m[0][j + 1] = max(m[0][j], f);
		}

		for (int i = 0; i < t1; i++) {
			for (int j = 0; j < t2; j++) {
				if (s1[i + 1] == s2[j + 1])
					m[i + 1][j + 1] = m[i][j] + 1;
				else
					m[i + 1][j + 1] = max(m[i][j + 1], m[i + 1][j]);
			}
		}

		cout << m[t1][t2] << endl;
	}
	return 0;
}