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;

const int N = 1e4 + 10;
long long n, q, m, tmp;
long long dp[N][N];
string s, p;
string a1, a2;

int main() 
{
	cin >> q;
	for (int x = 0; x < q; x++) {
	cin >> a1 >> a2;
	if (a1.size() > a2.size())
		s = a1, p = a2;
	else
		p = a1, s = a2;
	n = s.size();
	m = p.size();
	
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			if(s[i] == p[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[i + 1][j + 1] << '\n';
		}
	}
	cout << dp[n][m] << '\n';
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
usig 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;
 
}

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

#define _CRT_SECURE_NO_WARNINGS

#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)
#define REP2(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define REP3(i, x, n) for(decltype(x) i = (x); i <= (n); i++)
#define RREP(i, n) for (decltype(n) i = (n) - 1; i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

const int INF = 1000000000;
const double PI = 3.1415926535897932384626433832795;

// N, E, S, W
const int dx[4] = { -1, 0,  1,  0 };
const int dy[4] = { 0, 1,  0, -1 };

using LL = long long int;
using LD = long double;
using pii = pair<int, int>;
using pdd = pair<double, double>;
using pll = pair<LL, LL>;
using vi = vector<int>;
using vd = vector<double>;
using vvi = vector<vi>;
using vll = vector<LL>;

//==============================================
vvi dp(1050, vi(1050));

int lcs(string x, string y) {
	int ans = 0;
	int m = x.size();
	int n = y.size();

	x = ' ' + x;
	y = ' ' + y;
	REP3(i, 1, m) {
		REP3(j, 1, n) {
			if (x[i] == y[j]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			} else {
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
			}
			ans = max(ans, dp[i][j]);
		}
	}

	return ans;
}

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

	int q;
	cin >> q;

	string str1, str2;
	REP(i, q) {
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << "\n";
	}
	return 0;
}

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

#define REP(i, n) for(int (i) = 0; (i) < (n); (i)++)

string str1, str2;
int dp[1001][1001];
int k;

int solve(int i, int j)
{
  if(dp[i][j] > 0)
    return dp[i][j];
  if(i == str1.size() || j == str2.size()){
    if(i != str1.size()){
      return solve(i + 1, k);
    }else{
      return 1;
    }
  }
  if(str1[i] == str2[j]){
    k = j + 1;
    dp[i][j] = solve(i + 1, j + 1);
    return dp[i][j] + 1;
  }else{
    return solve(i, j + 1);
  }
}

int main()
{
  int q, n, ans = 0;
  cin >> q;
  cin.ignore();
  REP(i, q){
    getline(cin, str1);
    getline(cin, str2);
    if(str1.size() < str2.size())
      swap(str1, str2);
    fill(&dp[0][0], &dp[1001][0], -1);
    REP(j, str1.size()){
      n = solve(j, 0) - 1;
      ans = (n > ans) ? n : ans;
    }
    swap(str1, str2);
    fill(&dp[0][0], &dp[1001][0], -1);
    REP(j, str1.size()){
      n = solve(j, 0) - 1;
      ans = (n > ans) ? n : ans;
    }
    cout << ans << endl;
    ans = 0;
    fill(&dp[0][0], &dp[1001][0], -1);
  }
}

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;  // X[0] に空白を挿入
  Y = ' ' + Y;  // Y[0] に空白を挿入
  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;
}

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

int main(){
  int n;
  char x[1001],y[1001];
  int dp[1010][1010];
  
  //load n;
  cin >>n;
  for(int i=0;i<n;i++){
    //load string
    scanf("%s",x);
    scanf("%s",y);
    //dp
    for(int j=0;j<strlen(x);j++){
      for(int k=0;k<strlen(y);k++){
	if(x[j]==y[k]){
	  dp[j+1][k+1]=dp[j][k]+1;
	}

	else{
	  if(dp[j][k+1]>dp[j+1][k]){
	    dp[j+1][k+1]=dp[j][k+1];
	  }

	  else{
	    dp[j+1][k+1]=dp[j+1][k];
	  }


	}
      }
    }

    //print
    cout <<dp[strlen(x)][strlen(y)]<<endl;
  }



  return 0;
}