Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// if S[i-1] == T[j-1] {
				// 	dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				// } else {
				// 	dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				// }
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = 1001001001;
const int MOD = 1000000007;

template <typename T>
void print(const T &v);

int main()
{
    int n;
    cin >> n;
    for (int k = 0; k < n; k++)
    {
        string A, B;
        cin >> A >> B;
        int a = A.size();
        int b = B.size();
        vector<vector<int>> dp(b + 1, vector<int>(a + 1, 0));
        for (int i = 0; i < b; i++)
        {
            for (int j = 0; j < a; j++)
            {
                if (B[i] == A[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[b][a] << endl;
    }
    return 0;
}

// Use For Debug
template <typename T>
void print(T const &v)
{
    for (int i = 0; i < v.size(); i++)
    {
        if (i)
            cout << ' ';
        cout << v[i];
    }
    cout << 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;
}

C++: #include <vector>
#include <iostream>
              
void solve() {
  std::string X, Y;
  std::cin >> X >> Y;
  const int LX = X.size();
  const int LY = Y.size();
  std::vector<int> dp0(LY+1, 0), dp1(LY+1, 0);
  std::vector<int> *dp = &dp0;
  std::vector<int> *dp_ = &dp1;
  for (int i = 1; i < LX+1; i++) {
    std::swap(dp, dp_);
    for (int j = 1; j < LY+1; j++) {
      (*dp)[j] = std::max((*dp)[j-1], (*dp_)[j]);
      if (X[i-1] == Y[j-1]) {
        (*dp)[j] = std::max((*dp)[j], (*dp_)[j-1] + 1);
      }       
    }         
  }           
  std::cout << dp->back() << std::endl;
}             
              
int main() {  
  int N;      
  std::cin >> N;
  for (int i = 0; i < N; i++) {
    solve();  
  }           
}

C++: #include <iostream>
#include <string>
#include <stdio.h>
#include <algorithm>
#define MAX 1000


int lcs(std::string X, std::string Y) {
    int c[MAX+1][MAX+1];
    int maxl = 0;
    int m = X.size();
    int n = Y.size();
    for (int i = 1; i <= m; i++) {
        c[i][0] = 0;
    }
    for (int i = 1; i <= n; i++) {
        c[0][i] = 0;
    }
    X = ' ' + X;
    Y = ' ' + Y;
    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] = std::max(c[i-1][j], c[i][j-1]);
            }
            maxl = std::max(maxl, c[i][j]);
        }
    }
    return maxl;
}

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

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 = 0; 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>
using namespace std;
#define rep(i,a) for(int i=0;i<a;i++)
#define pd(a,n) for(int i=0;i<n;i++)cout<<a[i]<<((i==n-1)?"\n":" ");cout<<endl;
#define pdd(a,n,m)for(int i=0;i<n;i++){for(int j=0;j<m;j++)cout<<a[i][j]<<" ";cout<<endl;}
#define mp make_pair
#define pb push_back
#define ll long long
//#define __int64 long long
#define P pair<int,int>
#define PP pair<P,int>

int dp[1011][1011];

int query(string a,string b){
  int n=a.size();
  int m=b.size();

  rep(i,1011)rep(j,1011)dp[i][j]=0;

  rep(i,n){
    rep(j,m){
      if(a[i]==b[j]){
        dp[i+1][j+1]=max(dp[i+1][j+1],dp[i][j]+1);
      }
      dp[i][j+1]=max(dp[i][j+1],dp[i][j]);
      dp[i+1][j]=max(dp[i+1][j],dp[i][j]);
    }
  }
  int ret=0;
  rep(i,n+1)rep(j,m+1)ret=max(ret,dp[i][j]);

  return ret;
}
int main(){
  int q;
  cin>>q;
  rep(i,q){
    string a,b;
    cin>>a>>b;
    cout<<query(a,b)<<endl;
  }

  return 0;
}