KMP + 求最小循环节 --- POJ 2406 Power Strings

 Power Strings

Problem's Link:  http://poj.org/problem?id=2406

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Mean: 

给你一个字符串，让你求这个字符串最多能够被表示成最小循环节重复多少次得到。

analyse:

KMP之next数组的运用。裸的求最小循环节。

Time complexity: O(N)

 

Source code: 

/*
* this code is made by crazyacking
* Verdict: Accepted
* Submission Date: 2015-07-28-08.23
* Time: 0MS
* Memory: 137KB
*/
#include <queue>
#include <cstdio>
#include <set>
#include <string>
#include <stack>
#include <cmath>
#include <climits>
#include <map>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#define  LL long long
#define  ULL unsigned long long
using namespace std;
const int MAXN=1000010;
char s[MAXN];
int Next[MAXN];
void getNext(int len)
{
     Next[0]=0;
     for(int i=1,k=0;i<len;++i)
     {
           while(s[i]!=s[k] && k) k=Next[k-1];
           if(s[i]==s[k]) ++k;
           Next[i]=k;
     }
}
int main()
{
     ios_base::sync_with_stdio(false);
     cin.tie(0);
     while(~scanf("%s",s) && s[0]!='.')
     {
           int len=strlen(s);
           getNext(len);
           int min_cycle=len-Next[len-1];
           if(len%min_cycle!=0) printf("1\n");
           else printf("%d\n",len/min_cycle);
     }
     return 0;
}
/*

*/