Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

C++: #if 0
?????????X[0]???????????????????????\???????????¨??§???X[1],Y[1]???????????????????????????????????????
#endif

#include <iostream>
#include <string>
using namespace std;

int main(){
	int q;
	cin >> q;
	for(int a=0;a<q;++a){
		string X,Y;
		int L[1000+10][1000+10];
		cin >> X >> Y;
		for(int i=0;i<1000;++i) //???????????\????????????L????????????
			for(int j=0;j<1000;++j)
				L[i][j]=0;
	
		for(int j=1;j<X.size()+1;++j)
			for(int k=1;k<Y.size()+1;++k){
				if(X[j-1]==Y[k-1])
					L[j][k]=1+L[j-1][k-1];
				else
					L[j][k]=max(L[j-1][k],L[j][k-1]);
			}
		cout << L[X.size()][Y.size()] << endl;
	}
}

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

#define MAX 1024

int LCS[MAX][MAX];

void ini(){
}
int solve(string s1,string s2){
  if(s1.length() > s2.length())
	swap(s1,s2);
  for(int i=1;i<=s1.length();i++){
    for(int j=1;j<=s2.length();j++){
      if(s1[i-1]==s2[j-1])
	LCS[i][j]=LCS[i-1][j-1]+1;
      else
	LCS[i][j]=max(LCS[i][j-1],LCS[i-1][j]);
    }
  }
  return LCS[s1.length()][s2.length()];
}


int main(){
  string s1, s2;
  int n;
  cin >> n;
  for(int i=0;i<n;i++){
    for(int i=0;i<MAX;i++){
      for(int j=0;j<MAX;j++){
        LCS[i][j] = 0;
      }
    }
    cin>>s1>>s2;
    cout<<solve(s1,s2)<<endl;
    /*
    for(int i=0;i<=s1.length();i++){
      for(int j=0;j<=s2.length();j++){
	cout << LCS[i][j] << "  " ;
      }
      cout << endl;
    }*/
  }

}

C++: #include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
#include <functional>
#include <cctype>

using namespace std;

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

string X, Y;

void solve(int x_size, int y_size)
{
	vector< vector<int> > dp(x_size + 1, vector<int>(y_size + 1));

	for(int i = 0; i < x_size; ++i) {
		for(int j = 0; j < y_size; ++j) {
			if(X[i] == Y[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[x_size][y_size] << endl;
}

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

	int n;
	cin >> n;
	REP(i, n) {
		cin >> X >> Y;
		solve(X.size(), Y.size());
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;

#define rep(i, n) for (int i = 0; i < n; ++i)
#pragma region Debug
template <typename T>
void view(const std::vector<T> &v)
{
    for (const auto &e : v)
    {
        std::cout << e << " ";
    }
    std::cout << std::endl;
}
template <typename T>
void view(const std::vector<std::vector<T>> &vv)
{
    for (const auto &v : vv)
    {
        view(v);
    }
}
#pragma endregion
#pragma region chminmax
template <typename T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <typename T>
inline bool chmax(T &a, T b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
#pragma endregion

int main()
{
    int q;
    cin >> q;
    rep(d, q)
    {
        string s, t;
        cin >> s >> t;
        vector<vector<int>> dp(s.size() + 1, vector<int>(t.size() + 1));

        rep(i, s.size()) rep(j, t.size())
        {

            chmax(dp[i + 1][j + 1], dp[i][j] + (s[i] == t[j]));
            chmax(dp[i + 1][j + 1], dp[i + 1][j]);
            chmax(dp[i + 1][j + 1], dp[i][j + 1]);
        }
        cout << dp[s.size()][t.size()] << endl;
    }
    return 0;
}

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

void fnInput(vector<string>& rvsStrX, vector<string>& rvsStrY)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvsStrX.resize(nMaxSiz);
  rvsStrY.resize(nMaxSiz);

  for (int i = 0; i < nMaxSiz; ++i)
  {
    cin >> rvsStrX[i] >> rvsStrY[i];
    rvsStrX[i] = ' ' + rvsStrX[i];
    rvsStrY[i] = ' ' + rvsStrY[i];
  }
}

int fnLngCmnSubseq(const vector<string>& cnrvsStrX, const vector<string>& cnrvsStrY)
{
  vector<vector<int>> vvnLcsDP;
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    const int nMAXNX = cnrvsStrX[i].size();
    const int nMAXNY = cnrvsStrY[i].size();

    vvnLcsDP.clear();
    vvnLcsDP.resize(nMAXNX, vector<int>(nMAXNY, 0));

    for (int nx = 1; nx < nMAXNX; ++nx)
      for (int ny = 1; ny < nMAXNY; ++ny)
        if (cnrvsStrX[i][nx] == cnrvsStrY[i][ny])
          vvnLcsDP[nx][ny] = vvnLcsDP[nx - 1][ny - 1] + 1;
        else
          vvnLcsDP[nx][ny] = max(vvnLcsDP[nx - 1][ny], vvnLcsDP[nx][ny - 1]);

    cout << vvnLcsDP[nMAXNX - 1][nMAXNY - 1] << endl;
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<string> vsStrX, vsStrY;

  fnInput(vsStrX, vsStrY);
  fnLngCmnSubseq(vsStrX, vsStrY);
  return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back
#define INF (1e9+1)
//#define INF (1LL<<59)


int main(){
    int n;
    cin>>n;
    rep(i,n){
        string s,t;
        cin>>s>>t;
        
        
        int dp[1001][1001]={};
        
        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][j+1],dp[i+1][j]);
            }
        }
        
        cout<<dp[s.size()][t.size()]<<endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
typedef long long ll;
using namespace std;

int lcs(string x,string y){
  int xl=x.length(),yl=y.length();
  int dp[1001][1001],i,j;

  memset(dp,0,sizeof(dp));

  for(i=1;i<=xl;i++){
    for(j=1;j<=yl;j++){
      if(x[i-1]==y[j-1]){
        dp[i][j]=dp[i-1][j-1]+1;
      }
      else{
        dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
      }
    }
  }

  return dp[xl][yl];
}

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

  return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std ;
string s1,s2;
int n;
int count(string s,string t){
    int m=s.size(),p=t.size(),maxi=0;
    int x[1001][1001];
    for(int i=0;i<=m;i++) x[i][0]=0;
    for(int i=1;i<=p;i++) x[0][i]=0;
    s=' '+s; t=' '+t;
    for(int i=1;i<=m;i++){
        for(int j=1;j<=p;j++){
            if(s[i]==t[j]) x[i][j]=1+x[i-1][j-1];
            else x[i][j]=max(x[i-1][j],x[i][j-1]);
        }
    }
    return x[m][p];
}
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>s1>>s2;
        cout<<count(s1,s2)<<endl;
    }
    return 0;
}