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] = 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++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
//#include "MyMath.h"
//#include "DataStructure.h"
#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <functional>
#include <stdio.h>
using namespace std;
typedef pair<int, int> p;
const int INF = 1000000000;
int main(){
	int n; cin >> n;
	for (int k = 0; k < n; k++) {
		char s[1000], t[1000];
		scanf("%s",&s); scanf("%s", &t);
		int i = 0, j = 0;
		int dp[1001][1001];
		fill(dp[0], dp[1001], 0);
		int res = 0;
		while (s[i] != '\0'){
			while (t[j] != '\0') 
			{
				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]);
				res = dp[i + 1][j + 1];
				//cout << "i " << i << "j " << j << endl;
				//cout << "dp" << dp[i + 1][j + 1] << endl;
				j++;
			}
			i++;
			j = 0;
		}

		cout << res << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
using namespace std;
int main(){

    string a,b;
    int n,nmax;
    
    cin>>n;
    for(int i=0;i<n;i++){
        int dp[1000]={0},result=0;
        cin>>a>>b;
        for(int j=0;j<a.size();j++) if(b[0]==a[j]) dp[j]++;
        for(int j=1;j<b.size();j++){
            nmax=0;
            if(b[j]==a[0]) dp[0]=1;
            for(int k=1;k<a.size();k++){
                nmax=max(dp[k-1],nmax);
                if(b[j]==a[k]) dp[k]=nmax+1;
            }
        }
        nmax=0;
        for(int j=0;j<a.size();j++) nmax=max(dp[j],nmax);
        cout<<nmax<<endl;
        
    }
    
    return 0;
    
}

C++: #include <iostream> 
#include <cstring> 
using namespace std;
int c[1001][1001];

int lcs(string x, string y)
{
    int maxl = 0;
    for (int i = 0; i < x.size(); i++)
    {
        c[i][0] = 0;
    } 
    for (int i = 0; i < y.size(); i++)
    {
        c[0][i] = 0; 
    }
    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][j-1] + 1; 
            }else
            {
                c[i][j] = max(c[i][j-1], c[i-1][j]);
            }
            maxl = max(maxl, c[i][j]);
        } 
    } 
    return maxl;
}

int main()
{
    string x,y;
    int q;
    cin>>q;
    while(q--)
    {
        cin>>x>>y;
        int ans = lcs(x, y);
        cout<<ans<<endl;
    }
    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;
    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>
using namespace std;
#define rep(i, n) for(int i = 0;i < n;i++)
#define repr(i, n) for(int i = n;i >= 0;i--)
#define frep(i, m, n) for(int i = m;i < n;i++)
#define frepr(i, m, n) for(int i = m;i >= n;i--)
#define vsort(v) sort(v.begin(),v.end())
#define ll long long
#define inf 999999999
typedef vector<vector<int>> vvi;
typedef vector<int> vi;
typedef vector<string> vst;
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
typedef pair<int, P> PP;
typedef pair<ll, LP> LPP;

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

int main(){
    int q;
    cin >> q;
    rep(p,q){
       string x,y;
       cin >> x >> y;
       vvi dp(x.length(),vi(y.length(),inf));
       rep(i,x.length()){
           rep(j,y.length()){
               if(i==0&&j==0)dp[i][j]=(x[i]==y[j]);
               else if(i==0)dp[i][j]=max(dp[i][j-1],(int)(x[i]==y[j]));
               else if(j==0)dp[i][j]=max((int)(x[i]==y[j]),dp[i-1][j]);
               else if(x[i]==y[j])dp[i][j]=1+dp[i-1][j-1];
               else dp[i][j]=max(dp[i][j-1],dp[i-1][j]);
            //    cout << dp[i][j];
           }
        //    cout << endl;
       }
       cout << dp[x.length()-1][y.length()-1] << endl;
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
int main(){
  int n;
  cin>>n;
  while(n--){
  string  a,b;
  long n=0,i,c=0;
  cin>>a>>b;
  for(i=0;i<a.size();i++)if(a[i]==b[c])if(++n)c++;
  cout<<n<<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 = 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[i]) {
        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;
}