Go: ///
// File:  0528.go
// Author: ymiyamoto
//
// Created on Thu Mar 22 01:52:09 2018
//
package main

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

var S, T string
var dp [4001][4001]int

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	for {
		scanner.Scan()
		S = scanner.Text()
		if len(S) == 0 {
			return
		}

		scanner.Scan()
		T = scanner.Text()

		for i := range dp {
			for j := range dp[i] {
				dp[i][j] = 0
			}
		}

		dp[0][0] = 0
		for i := range S {
			for j := range T {
				if S[i] == T[j] {
					dp[i+1][j+1] = max(dp[i+1][j], max(dp[i][j+1], dp[i][j]+1))
				} else {
					dp[i+1][j+1] = 0
				}
			}
		}
		var m int
		for i := range dp {
			for j := range dp[i] {
				m = max(m, dp[i][j])
			}
		}
		fmt.Println(m)
	}
}

C++: //JOI 0528 Common Sub-String
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main() {
	while(1){
		string s, t; int roop1=0, roop2 = 0, save[64000]={}, ans = 0;
		cin>>s;
		cin>>t;
		if(cin.eof())
		break;
	for (int i = 0; i<s.size(); i++){
		for (int j = 0; j<t.size(); j++){
			if (s[i] == t[j]){
				roop1 = 0;
				save[roop2] = 0;
				while (1){
					if (s[i + roop1] == 0 || t[j + roop1] == 0){
						break;
					}
					else{
						if (s[i + roop1] == t[j + roop1]){
							save[roop2] += 1;
							roop1++;
						}
						else if (s[i + roop1] != t[j + roop1]){
							roop2++;
							break;
						}
					}
				}
			}
		}
	}
	sort(save, save + roop2 + 1);
	ans = save[roop2];
	cout << ans << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<map>
#include<functional>
#include<queue>
using namespace std;
int main() {
	string a, b;
	while (cin >> a >> b) {
		int sum = 0;
		for (int i = 0; i < a.length(); i++) {
			for (int j = 0; j < b.length(); j++) {
				if (a[i] == b[i]) {
					int i2 = i, j2 = j;
					int l = 0;
					while (a[i2] == b[j2]) {
						l++;
						i2++;
						j2++;
					}
					sum = max(sum, l);
				}
			}
		}
		cout << sum << endl;
	}
}

C++: #include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
using namespace std;
int main(void){
  string a,b;
  while(cin >> a >> b){
    int ans = 0;
    for(int i = 0; i < (int)a.size(); i++){
      int c = 0;
      int t = 0;
      for(int j = 0; j < (int)a.size() - i && j < (int)b.size(); j++){
	if(a[i+j] == b[j]){
	  c++;
	}else{
	  t = max(t,c);
	  c = 0;
	}
      }
      ans = max(max(t,c),ans);
    }
    cout << ans << endl;
  }
}

C++: #include<bits/stdc++.h>
#pragma warning(disable:4996)
using namespace std;
using ll = long long;
const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int main() {
	string s, t;
	while (cin >> s >> t) {
		int s_size = s.size();
		int t_size = t.size();
		int ans = 0;

		for (int i = 0; i < s.size(); i++) {//sをずらしていく
			vector<int>a0(t.size());
			for (int j = 0; j < t.size(); j++) {
				if (j < t.size() && j + i < s.size() && t[j] == s[j + i]) {
					a0[j]++;
				}
				else if (j < t.size() && j + i < s.size() && t[j] != s[j + i]) {
					continue;
				}
			}
			int nagasa = 0;
			int x = 0;
			for (int i = 0; i < t.size(); i++) {
				int nagasa2 = 0;
				x = i;
				while (x < a0.size() && a0[x] == 1) {
					x++;
					nagasa2++;
				}
				nagasa = max(nagasa, nagasa2);
			}
			ans = max(ans, nagasa);
		}

		for (int i = 0; i < t.size(); i++) {//tをずらしていく
			vector<int>a0(s.size());

			for (int j = 0; j < s.size(); j++) {
				if (j < s.size() && j + i < t.size() && s[j] == t[j + i]) {
					a0[j]++;
				}
				else if (j < s.size() && j + i < t.size() && s[j] != t[j + i]) {
					continue;
				}
			}
			int nagasa = 0;
			int x = 0;
			for (int i = 0; i < t.size(); i++) {
				int nagasa2 = 0;
				x = i;
				while (x < a0.size() && a0[x] == 1) {
					x++;
					nagasa2++;
				}
				nagasa = max(nagasa, nagasa2);
			}
			ans = max(ans, nagasa);
		}
		cout << ans << endl;
	}
}

C++: #include <iostream>
#include <iomanip>
#include <vector>
#include <set>
#include <map>
#include <list>
#include <iterator>
#include <queue>
#include <stack>
#include <deque>
#include <sstream>
#include <algorithm>
#include <numeric>
#include <string>
#include <cmath>
#include <complex>
#include <functional>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cassert>
#include <cstdlib>
#include <cctype>

#define REP(i,m,n) for(int i=m;i<(int)n;i++)
#define rep(i,n) for(int i=0;i<(int)n;i++)
#define rrep(i,n) for(int i = 1; i <= n; i++)
#define drep(i,n) for(int i = n; i >= 0; i--)
#define rp(i,c) rep(i,(int)c.size())
#define fr(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();i++)
#define mp make_pair
#define pb push_back
#define all(c) (c).begin(),(c).end()
#define rall(u) (u).rbegin(),(u).rend()
#define dbg(x) cerr<<#x<<" = "<<(x)<<endl
#define v_delete(a,b) (a).erase(remove((a).begin(), (a).end(), b), (a).end())
#define v_unique(a) (a).erase(unique((a).begin(), (a).end()), (a).end())
#define VV(T) vector<vector< T > >
#define init(a,b) memset((a), (b), sizeof((a)))
using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
const int inf=1<<28;
const double INF=1e10,EPS=1e-9;


template<class T>int SIZE(T a){return a.size();}
template<class T>string IntToString(T num){string res;stringstream ss;ss<<num;return ss.str();}
template<class T>T StringToInt(string str){T res=0;for(int i=0;i<SIZE(str);i++)res=(res*10+str[i]-'0');return res;}
template<class T>T gcd(T a,T b){if(b==0)return a;return gcd(b,a%b);}
template<class T>T lcm(T a,T b){return a/gcd(a,b)*b;}

template <class T> void input(T& a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }
template <class T> void input(T* a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }

int dp[4002][4002];
int main(){
	string a,b;
	while(cin >> a >> b){
		memset(dp,0,sizeof(dp));
	int as=a.size();
	a+='a';
	int bs=b.size();
	b+='b';
	int ans=0;
	for(int i=0;i<as;i++){
		for(int j=0;j<bs;j++){
			if(a[i+1]==b[j+1]){
				dp[i+1][j+1]=dp[i][j]+1;
			}else{
				dp[i+1][j+1]=0;
			}/*
			if(dp[i+1][j+1]){
				cout << dp[i+1][j+1]<<endl;
				cout << i << "," << j << endl;
			}*/
			ans=max(ans,dp[i+1][j+1]);
		}
	}
	cout << ans << endl;
	}
	return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define INF (1<<30)
#define INFLL (1ll<<60)
typedef pair<int, int> P;
typedef pair<ll, P> E;
#define MOD (1000000007ll)
#define l_ength size
#define PI 3.14159265358979
 
void mul_mod(ll& a, ll b){
    a *= b;
    a %= MOD;
}
 
void add_mod(ll& a, ll b){
    b += MOD;
    a += b;
    a %= MOD;
}

int n,m;
int memo[4444][4444];
bool done[4444][4444];
char s[4444],t[4444];

int dp(int i, int j){
    if(done[i][j]){
        return memo[i][j];
    }
    done[i][j] = true;
    if(i == n || j == m){
        memo[i][j] = 0ll;
    }else if(s[i] != t[j]){
        memo[i][j] = 0ll;
    }else{
        memo[i][j] = dp(i+1,j+1) + 1;
    }
    return memo[i][j];
}

int main(void){
    int i,j;
    ll ans;
    while(scanf("%s",s)!=EOF){
        fill(done[0],done[4444],false);
        ans = 0ll;
        scanf("%s",t);
        n = strlen(s); m = strlen(t);
        for(i=0; i<n; ++i){
            for(j=0; j<m; ++j){
                ans = max(ans,dp(i,j));
            }
        }
        cout << ans << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 100000005
#define MAX 5001
using namespace std;
//__gcd(a,b), __builtin_popcount(a);

int dp[4005][4005];
int main(){
	string s1, s2;
	while(cin >> s1 >> s2){
	s1 = " " + s1;s2 = " " + s2;
	fill((int*)dp, (int*)(dp+4005), 0);
	int ans = 0;
	for(int i = 1;i <= s1.size();i++){
		for(int j = 1;j <= s2.size();j++){
			if(s1[i] == s2[j])dp[i][j] = dp[i-1][j-1]+1;
			ans = max(ans, dp[i][j]);
		}
	}
	cout << ans << endl;
	}
	return 0;
}