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++: /**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author NikuKyabe
 */

#include <iostream>
#include <string>
#include <vector>
using namespace std;
#define int long long
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define REP(i,n)  FOR(i,0,(n))
typedef vector<int> vec;
typedef vector< vector<int> > mat;


class Longest_Common_Subsequence {
public:
	void solve(std::istream& in, std::ostream& out) {
	  int q;
	  in >> q;
	  REP(i, q){
	    string x,y;
	    in >> x >> y;
	    mat dp = mat(x.length()+1, vec(y.length()+1, 0));
	    REP(j,x.length())REP(k,y.length()){
	      if(x[j] == y[k]){
	        dp[j + 1][k + 1] = dp[j][k] + 1;
	      }
	      else{
	        dp[j + 1][k + 1] = max(dp[j][k + 1], dp[j + 1][k]);
	      }
	    }
	    out << dp[x.length()][y.length()] << endl;
	  }
	}
};


signed main() {
  ios::sync_with_stdio(false);
  cout.tie(0);
  cout << fixed;
	Longest_Common_Subsequence solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
static const int N=1001;
int lcs(string X,string Y){
  int c[N][N] = {};
  int m=X.size();
  int n=Y.size();

  int max1=0;
  X=' '+X;
  Y=' '+Y;

  //for(int i=1;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]);
      }
      max1=max(max1,c[i][j]);
    }
  }
  return max1;
}

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;
}

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

string s, t;
int dp[1001][1001];
int main()
{
    int p;
    cin >> p;
    while(p>0)
    {
        p--;
        cin >> s >> t;
        int n = s.size();
        int m = t.size();
        for (int i = 1; i <= n; i++)
            dp[i][0] = 0;
        for (int i = 1; i <= m; i++)
            dp[0][i] = 0;
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= m; j++) {
                if (s[i - 1] == t[i - 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];
                }
            }
        }
        cout << dp[n][m] << endl;
    }

}

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

static 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;
  C[0][0] = 0;
  for ( int i = 1; 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]);
    }
  }javascript:void(0)

  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;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define _USE_MATH_DEFINES
#include <math.h>
#define rep(i,n) for(int i = 0;i < n;i++)
#define NIL = -1;

ll gcd(long long a,long long b) {
    if (a < b) swap(a,b);
    if (b == 0) return a;
    
    return gcd(b,a%b);
}

ll lcm(ll a,ll b){
    a / gcd(a,b) * b;
}
const ll mod = 1e9 + 7;

int dx[4] = {0,1,0,-1};
int dy[4] = {1,0,-1,0};

const ll INF = 1e9;
/////////////////////////////////////////////////////////////////////////////////////////
int n,m;
string s,t;
int dp[2000][2000];
void solve(){
    for (int i = 0;i < n;i++){
        for (int j = 0;j < m;j++){
            if (s[i] == t[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[n][m] << endl;
}
int main(){
    int q;
    cin >> q;
    vector<string> x(q),y(q);
    vector<int> ans(q);
    

    for (int i = 0;i < q;i++){
        cin >> s >> t;
        n = s.size();
        m = t.size();
        solve();
    }

    return 0;
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<vector>
#include<functional>
#include<iomanip>
#include<queue>
#include<cassert>
#include<tuple>
#include<set>
#include<map>
#include<list>
#include<bitset>

#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;

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

const int dx[4] = { 1, 0, -1, 0 };
const int dy[4] = { 0, 1, 0, -1 };
const int INF = (int)1e9;

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 <bits/stdc++.h>
using namespace std;

template<class T> inline void chmax(T &a, const T &b) { if(a < b) a = b; }

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

	int q;
	cin >> q;

	while(q--) {
		string a, b;
		cin >> a >> b;

		const int n = a.size();
		const int m = b.size();

		vector<vector<int>> dp(n + 2, vector<int>(m + 2, 0));
		for(int i = 0; i <= n; ++i) {
			for(int j = 0; j <= m; ++j) {
				if(a[i] == b[j]) {
					chmax(dp[i + 1][j + 1], dp[i][j] + 1);
				}
				else {
					chmax(dp[i + 1][j + 1], dp[i][j]);
					chmax(dp[i + 1][j], dp[i][j]);
					chmax(dp[i][j + 1], dp[i][j]);
				}
			}
		}

		cout << dp[n][m] << endl;
	}

	return EXIT_SUCCESS;
}

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

constexpr int MAX_XY = 1010;

int lx, ly, q, dp[MAX_XY][MAX_XY];
std::string sx, sy;

void fill_dp(){
    for(int i = 1; i <= lx; ++i){
        for(int j = 1; j <= ly; ++j){
            if(sx[i - 1] == sy[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1;
            else dp[i][j] = std::max(dp[i - 1][j], dp[i][j - 1]);
        }
    }
}

void solve(){
    fill_dp();
    std::cout << dp[lx][ly] << std::endl;
    return;
}

int main(){
    std::cin >> q;
    
    for(int i = 0; i < q; ++i){
        std::cin >> sx >> sy;
        lx = sx.size(), ly = sy.size();
        solve();
    }
    return 0;
}