HUST - 1010KMP最小循环节性质

There is a string A. The length of A is less than 1,000,000. I rewrite it again and again. Then I got a new string: AAAAAA...... Now I cut it from two different position and get a new string B. Then, give you the string B, can you tell me the length of the shortest possible string A.
For example, A="abcdefg". I got abcd efgabcdefgabcdefgabcdefg.... Then I cut the red part: efgabcdefgabcde as string B. From B, you should find out the shortest A.

Input

Multiply Test Cases.
For each line there is a string B which contains only lowercase and uppercase charactors.
The length of B is no more than 1,000,000.

Output

For each line, output an integer, as described above.

Sample Input

bcabcab
efgabcdefgabcde

Sample Output

3
7

#include <iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<stdio.h>
#include<string.h>
#include<algorithm>
//KMP-性质
//本题利用KMP算法中求Next[]数组的性质可以解决；
//即如果一个字符串为循环串时，（例如adcabcabc）
//那么它的next[]数组满足下面性质：
//1、len%(len-p[len])==0;
//2、len/(len-p[len])就是循环的次数；
//这里len是字符串的长度，p[]是next[]数组；
//刚开始，想的有点挫每次都执行一次Getp函数 ，结果果断超时，最后发现其实一次GetP函数后；只需判断该题中
//字符串前缀能否满足上述两个条件即可；还有就是循环次数不可能为一次；这一点需要注意；(所以就需在判断
//满足条件1后在判断是否len/(len-p[len])=1;等于说明此时的前缀不是周期串；否则就是；直接打印输出即可。
#include<stdio.h>
#include <iostream>
#include<string.h>
#include<math.h>
int p[1000010];
char str[1000010];
void getp(int len)      //getp函数，求字符串的next[]数组值
{
    //这里我把next[]该成了p[]；其实一样。
    int i=0,j=-1;
    p[i]=j;
    while(i<len)
    {
        if(j==-1||str[i]==str[j])
        {
            i++;
            j++;
            p[i]=j;
        }
        else
            j=p[j];
    }
}
int main()
{
    int n,i,j,ca=1;
    while(scanf("%s",str))
    {
        n=strlen(str);
        getp(n);
        int len=n-p[n];
        //if(n%len==0)
       printf("%d\n",len);
    }
    return 0;
}

HUST - 1010KMP最小循环节性质

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