kmp（循环节）

Cyclic Nacklace

Problem Description

CC always becomes very depressed at the end of this month, he has checked his credit card yesterday, without any surprise, there are only 99.9 yuan left. he is too distressed and thinking about how to tide over the last days. Being inspired by the entrepreneurial spirit of "HDU CakeMan", he wants to sell some little things to make money. Of course, this is not an easy task.

As Christmas is around the corner, Boys
are busy in choosing christmas presents to send to their girlfriends.
It is believed that chain bracelet is a good choice. However, Things are
not always so simple, as is known to everyone, girl's fond of the
colorful decoration to make bracelet appears vivid and lively, meanwhile
they want to display their mature side as college students. after CC
understands the girls demands, he intends to sell the chain bracelet
called CharmBracelet. The CharmBracelet is made up with colorful pearls
to show girls' lively, and the most important thing is that it must be
connected by a cyclic chain which means the color of pearls are cyclic
connected from the left to right. And the cyclic count must be more than
one. If you connect the leftmost pearl and the rightmost pearl of such
chain, you can make a CharmBracelet. Just like the pictrue below, this
CharmBracelet's cycle is 9 and its cyclic count is 2:

Now
CC has brought in some ordinary bracelet chains, he wants to buy
minimum number of pearls to make CharmBracelets so that he can save more
money. but when remaking the bracelet, he can only add color pearls to
the left end and right end of the chain, that is to say, adding to the
middle is forbidden.
CC is satisfied with his ideas and ask you for help.

 

Input

The first line of the input is a single integer T ( 0 < T <= 100 ) which means the number of test cases.
Each
test case contains only one line describe the original ordinary chain
to be remade. Each character in the string stands for one pearl and
there are 26 kinds of pearls being described by 'a' ~'z' characters. The
length of the string Len: ( 3 <= Len <= 100000 ).

 

Output

For each case, you are required to output the minimum count of pearls added to make a CharmBracelet.

 

Sample Input

3
aaa
abca
abcde

 

Sample Output

0
2
5

 

Author

possessor WC

 

Source

HDU 3rd “Vegetable-Birds Cup” Programming Open Contest

 

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题目大意：给一串字符串，问至少添加多少个字符，使得这个字符串有至少两个循环节

符合 i % ( i - next[i] ) == 0 && next[i] != 0 , 则说明字符串循环，而且

循环节长度为:   i - next[i]
循环次数为:       i / ( i - next[i] )

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <algorithm>
#include <iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include <stdio.h>
#include <string.h>
using namespace std;
const int N =  ;
int c[N] ;
int n ;
//int p[220009] ;
char a[] ;
char b[];

void getnext(char *b , int *next)
{
    int len = strlen(b);
    next[] = -  ;
    int k = -  , j =  ;
    while(j < len)
    {
        if(k == - || b[j] == b[k])
        {
            k++;
            j++;
            if(b[j] != b[k])
                next[j] = k;
            else
            {
               next[j] = next[k];
            }
        }
        else
            k = next[k];
    }
}

int main()
{
   int n ;
   cin >> n ;
   while(n--)
   {
       int next[];
       scanf("%s" , a);
       int len = strlen(a);
       getnext(a , next);
       int l = len - next[len];
       int ans =  ;
       if(len != l && len % l == )
       {
           printf("0\n");
       }
       else
       {
          // cout << l << " " << next[len] <<endl ;
           ans = l - len%l ;
           printf("%d\n" , ans);
       }
   }

    return  ;
}