KMP + 求最小循環節 --- HDU 1358 Period

Period 

Problem's Link:  http://acm.hdu.edu.cn/showproblem.php?pid=1358

---

 

Mean: 

給你一個字符串，讓你從第二個字符開始判斷當前長度的字符串是不是重複串，若是是，輸出當前位置，並輸出重複串的週期。

analyse:

仍是next數組的運用，詳見上一篇博客。

Time complexity: O(N)

 

Source code: 

/*
* this code is made by crazyacking
* Verdict: Accepted
* Submission Date: 2015-07-28-07.12
* 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;
int n;
char s [ MAXN ];
int Next [ MAXN ];
void getNext()
{
      Next [ 0 ] = 0;
      for( int i = 1 , k = 0; i <n; ++ 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);
      int cas = 1;
      while( ~ scanf( "%d" , &n) &&n)
      {
            scanf( "%s" ,s);
            getNext();
            printf( "Test case #%d \n " , cas ++);
            for( int i = 1; i <n; ++ i)
            {
                  int now_cycle =( i + 1) - Next [ i ];
                  if(( now_cycle != i + 1) && ( i + 1) % now_cycle == 0)
                  {
                        printf( "%d %d \n " , i + 1 ,( i + 1) / now_cycle);
                  }
            }
            puts( "");
      }
      return 0;
}
/*

*/