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2012-02-22 07:19:35Morris

[UVA] 10298 - Power Strings

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Problem D: Power Strings

Given two strings a and b we define a*b to be their concatenation. For example, if a = "abc" and b = "def" then a*b = "abcdef". If we think of concatenation as multiplication, exponentiation by a non-negative integer is defined in the normal way: a^0 = "" (the empty string) and a^(n+1) = a*(a^n).

Each test case is a line of input representing s, a string of printable characters. For each s you should print the largest n such that s = a^n for some string a. The length of s will be at least 1 and will not exceed 1 million characters. A line containing a period follows the last test case.

Sample Input

abcd
aaaa
ababab
.

Output for Sample Input

1
4
3

做法 : KMP



#include<stdio.h>
#include<string.h>
#define MaxL 10000001
int KMP_init(char *B) {
	int i, j;
	int P[MaxL];
	P[0] = -1, i = 1, j = -1;
	while(B[i]) {
		while(j >= 0 && B[j+1] != B[i])
			j = P[j];
		if(B[j+1] == B[i])
			++j;
		P[i] = j, ++i;
	}
	return j;
}
main() {
	char s[MaxL];
	while(gets(s)) {
		if(s[0] == '.' && s[1] == '\0')
			break;
		int n = strlen(s), t = KMP_init(s);
		if(n%(n-t-1) == 0)
			printf("%d\n", n/(n-t-1));
		else
			puts("1");
	}
	return 0;
}