Period-蒲公英云

Period

女爷i 2022-08-10 08:41 143阅读 0赞

Period

Time Limit: 1000ms Memory limit: 65536K 有疑问？点这里^_^

题目描述

For each prefix of a given string S with N characters (each character has an

ASCII code between 97 and 126, inclusive), we want to know whether the prefix

is a periodic string. That is, for each i (2 ≤ i ≤ N) we want to know the largest K

1 (if there is one) such that the prefix of S with length i can be written as AK ,

that is A concatenated K times, for some string A. Of course, we also want to

know the period K.

输入

The input file consists of several test cases. Each test case consists of two

lines. The first one contains N (2 <= N <= 1 000 000) – the size of the string S.

The second line contains the string S. The input file ends with a line, having the

number zero on it.

输出

For each test case, output “Test case #” and the consecutive test case

number on a single line; then, for each prefix with length i that has a period K >

1, output the prefix size i and the period K separated by a single space; the

prefix sizes must be in increasing order. Print a blank line after each test case.

示例输入

3
aaa
12
aabaabaabaab
0

示例输出

Test case #1
2 2
3 3
Test case #2
2 2
6 2
9 3
12 4

提示

来源

Southeastern European Regional Programming Contest

示例程序

#include<stdio.h>  
#include<string.h>  
#define N 1000005  
char str[N];  
int f[N];  
void getFail(char *p, int *f)  
{  
    int m=strlen(p);  
    f[0]=f[1]=0;  
    for(int i=1; i<m; ++i)  
    {  
        int j=f[i];  
        while(j && p[i]!=p[j])j=f[j];  
        f[i+1] = p[i]==p[j]?1+j:0;  
    }  
}  
int main()  
{  
    int n,cas=0;  
    while(scanf("%d",&n))  
    {  
        if(n==0)  
            break;  
        cas++;  
        getchar();  
        memset(str,0,sizeof(str));  
        for(int i=0; i<n; i++)  
            scanf("%c",&str[i]);  
        getFail(str,f);  
         printf("Test case #%d\n",cas);  
        for(int i=2; i<=n; i++)  
        {  
            if(f[i]>0&&i%(i-f[i])==0)  
                printf("%d %d\n",i,i/(i-f[i]));  
        }  
        printf("\n");  
    }  
    return 0;  
}