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 MAX 1000

int dp[MAX+1][MAX+1];

int lcs(char x[], char y[]){
  for(int i = 0; i<=strlen(x); i++){
    dp[i][0] = 0;
    dp[0][i] = 0;
  }

  for(int i = 1; i<=strlen(x); i++){
    for(int j = 1; j<=strlen(y); j++){
      dp[i][j] = (x[i] == y[j]) ? dp[i-1][j-1] + 1 :
                                  max(dp[i-1][j],dp[i][j-1]);
    }
  }

  return dp[strlen(x)][strlen(y)];
}

int main(){

  int q;
  scanf("%d", &q);

  char X[MAX + 1];
  char Y[MAX + 1];
  for(int i=0; i<q; i++){
    scanf("%s\n%s\n", X, Y);
    printf("%d\n", lcs(X, Y));
  }

  return 0;
}

C++: #include <bits/stdc++.h>
#include <math.h>
#include <vector>
#include <queue>
#include <iomanip>
#include <string>
#include <algorithm>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define rep_1 (i,j,n) for(int i=j;i<n;i++)
typedef long long ll;
typedef long l;
const ll l_INF = 1010101010101010;
const int INF = 1010101010;
const int dx[] = {-1,0,1,0,-1,-1,1,1};
const int dy[] = {0,-1,0,1,1,-1,1,-1};

int main(){
  int q; cin>>q;
  rep(x,q){
    string s,t; cin>>s>>t;
    int dp[1010][1010];
    int n=s.size(),m=t.size();
    rep(i,n+1){
      rep(j,m+1){
        dp[i+1][j+1]=max(dp[i][j+1],dp[i+1][j]);
        if(s[i]==t[j])dp[i+1][j+1]=max(dp[i][j]+1,dp[i+1][j+1]);
      }
    }
    /*if(x==3){
      rep(i,n+1){
        rep(j,m+1){
          cout<<dp[i][j];
        }
        cout<<endl;
      }
    }*/
    cout<<dp[n][m]<<endl;
  }
}

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

string x;
string y;

int lcs(string x, string y){

  int c[1024][1024] = {{}};
  string nul = "0";
  x = nul + x;
  y = nul + y;


  /*
  for(int i = 0;i < x.size();i++) cout << " " << x[i];
  cout << endl;
  for(int i = 0;i < y.size();i++) cout << " " << y[i];
  cout << endl;
*/
  for(int i = 1;i < x.size();i++){
    for(int j = 1;j < y.size();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]);

/*
      for(int k = 1;k < x.size();k++){
        for(int l = 1;l < y.size();l++){
          cout << c[k][l] << ' ';
        }
        cout << endl;
      }
*/

    }
  }

  return c[x.size() - 1][y.size() - 1];
}



int main(){
  int q;
  cin >> q;

  for(int i = 0;i < q;i++){
    cin >> x;
    cin >> y;
    cout << lcs(x,y) << endl;
  }
}

C++: #include<cstdio>
#include<iostream>
#include<string>
#include<algorithm>
using namespace std;
#define N 1000

int lcs(string X,string Y){
  int c[N+1][N+1];
  int m=X.size();
  int n=Y.size();
  int maxcost=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]);
      }
      maxcost=max(maxcost,c[i][j]);
    }
  }
  return maxcost;
}

int main(){
  string s1,s2;
  int n;
  scanf("%d", &n);
  for(int i=0;i<n;i++){
    cin >> s1 >>s2;
    printf("%d\n",lcs(s1,s2));
  }
  return 0;
}

C++: /**
 * @Author: yujirotakahashi
 * @Date:   2020-05-17T20:21:41+09:00
 * @Last modified by:   yujirotakahashi
 * @Last modified time: 2020-05-25T03:33:07+09:00
 */

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

/*******  All Required define Pre-Processors and typedef Constants *******/
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define rep(i,n) for(int i=0; i<(n); ++i)
#define rep1(i,n) for(int i=1; i<=(n); ++i)
#define Dcout(a) cout << setprecision(20) << a << endl
#define MP make_pair
#define PB push_back
#define EPS 1e-9
#define PI 3.1415926535897932384626433832795
#define MOD 1000000007
//const ll INF = (1LL << 60);
//const double pi=acos(-1.0);
using ll = long long;
using PAIR = pair<int, int>;
#define debug cout << "line : " << __LINE__ << " debug" << endl
/****** Template of some basic operations *****/
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
/**************************************/

/******** User-defined Function *******/
using Graph = vector<vector<int>>;
int dx[4] = {-1,0,0,1};
int dy[4] = {0,1,-1,0};
/**************************************/

/********** Main()  function **********/
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  int q; cin >> q;

  int dp[1010][1010];
  rep(k,q){
      string x,y; cin >> x >> y;
      memset(dp, 0 ,sizeof(dp));

      dp[0][0] = 0;
      rep(i,x.size()){
          rep(j,y.size()){
              if(x[i]==y[j]){
                  chmax(dp[i+1][j+1],dp[i][j]+1);
              }else{
                  chmax(dp[i+1][j+1],dp[i+1][j]);
                  chmax(dp[i+1][j+1],dp[i][j+1]);
              }
          }
      }
      cout << dp[x.size()][y.size()] << endl;
  }

  return 0;
}
/********  Main() Ends Here *************/

C++: #include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
#define MAX_SEQ 1000

int main() {
  int n; cin >> n;

  for(int i=0;i<n;i++) {
    int subseq_len = 0;
    char seq1[MAX_SEQ+1];
    char seq2[MAX_SEQ+1];
    vector<char> seq_sub;
    cin >> seq1;
    cin >> seq2;

    for(int seq1_it=0;seq1[seq1_it]!='\0';seq1_it++) {
      vector<char>::iterator it = find(seq_sub.begin(), seq_sub.end(), seq1[seq1_it]);
        if (it == seq_sub.end()) {
          seq_sub.push_back(seq1[seq1_it]);
        }
    }
    for(int seq2_it=0;seq2[seq2_it]!='\0';seq2_it++) {
      vector<char>::iterator it = find(seq_sub.begin(), seq_sub.end(), seq2[seq2_it]);
        if (it != seq_sub.end()) {
          seq_sub.erase(it);
          subseq_len++;
        }
    }
    cout << subseq_len << 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;
  
  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]);
    }
  }
  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;
}