poj 3080 Blue Jeans (n个字符串的最长公共子串，暴力+kmp)

  1/* ***********************************************
  2Author :111qqz
  3Created Time :2016年08月11日 星期四 01时29分02秒
  4File Name :code/poj/3080.cpp
  5************************************************ */
  6
  7#include <cstdio>
  8#include <cstring>
  9#include <iostream>
 10#include <algorithm>
 11#include <vector>
 12#include <queue>
 13#include <stack>
 14#include <set>
 15#include <map>
 16#include <string>
 17#include <cmath>
 18#include <cstdlib>
 19#include <deque>
 20#include <ctime>
 21#define fst first
 22#define sec second
 23#define lson l,m,rt<<1
 24#define rson m+1,r,rt<<1|1
 25#define ms(a,x) memset(a,x,sizeof(a))
 26typedef long long LL;
 27#define pi pair < int ,int >
 28#define MP make_pair
 29
 30using namespace std;
 31const double eps = 1E-8;
 32const int dx4[4]={1,0,0,-1};
 33const int dy4[4]={0,-1,1,0};
 34const int inf = 0x3f3f3f3f;
 35const int N=70;
 36int nxt[N];
 37string dna[15];
 38int n ;
 39void getnxt( string a)
 40{
 41    int i = 0 ;
 42    int j = -1;
 43    int n = a.length();
 44    nxt[0] = -1;
 45    while (i<n)
 46	if (j==-1||a[i]==a[j]) nxt[++i]=++j;
 47	else j = nxt[j];
 48}
 49bool kmp(string a,string b)
 50{
 51    int m = a.length();
 52    int n = b.length();
 53    getnxt(a);
 54    int i = 0;
 55    int j = 0;
 56    while (i<n)
 57    {
 58	if (j==-1||a[j]==b[i]) i++,j++;
 59	else j=nxt[j];
 60	if (j==m) return true;
 61    }
 62    return false;
 63}
 64int main()
 65{
 66	#ifndef  ONLINE_JUDGE 
 67	freopen("code/in.txt","r",stdin);
 68  #endif
 69	int T;
 70	ios::sync_with_stdio(false);
 71	cin>>T;
 72	while (T--)
 73	{
 74	    cin>>n;
 75	    for ( int i = 1 ; i <= n ; i++) cin>>dna[i];
 76	    string ans="";
 77	    int len = dna[1].length();
 78	    //cout<<"len:"<<len<<endl;
 79	    for ( int i = 0 ; i < len ; i++)
 80		for ( int j = 1 ; i+j-1 < len ;j++)
 81		{
 82		    bool match = true;
 83		    string tmp = dna[1].substr(i,j);
 84		   // cout<<"tmp:"<<tmp<<endl;
 85
 86		    for ( int k = 2 ; k <= n; k++)
 87			if (!kmp(tmp,dna[k]))
 88			{
 89			    match = false;
 90			    break;
 91			}
 92		    if (match)
 93		    {
 94	//		cout<<"ccc"<<endl;
 95			if (tmp.length()>ans.length())
 96			    ans = tmp;
 97			else if (tmp.length()==ans.length()&&tmp<ans)
 98			    ans = tmp;
 99		    }
100		}
101		    if (ans.length()<3)
102			cout<<"no significant commonalities"<<endl;
103		    else
104		        cout<<ans<<endl;
105
106	}
107
108  #ifndef ONLINE_JUDGE  
109  fclose(stdin);
110  #endif
111    return 0;
112}