POJ 2406 Power Strings 求連續重複字串(kmp)
阿新 • • 發佈:2019-01-22
Power Strings
Each test case is a line of input representing s, a string of printable characters. 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.
kmp的next陣列具有此性質:一個串的最小迴圈節長度是len-next[len]。
如果len%(len-next[len])==0,那麼這個字串的最小週期就是:len/(len-next[len]).
Time Limit:3000MS | Memory Limit:65536K |
Total Submissions:29827 | Accepted:12456 |
Description
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).Input
Output
For each s you should print the largest n such that s = a^n for some string a.Sample Input
abcd aaaa ababab .
Sample Output
1 4 3
Hint
This problem has huge input, use scanf instead of cin to avoid time limit exceed.Source
kmp的next陣列具有此性質:一個串的最小迴圈節長度是len-next[len]。
如果len%(len-next[len])==0,那麼這個字串的最小週期就是:len/(len-next[len]).
//5248K 110MS #include<stdio.h> #include<string.h> #define M 1000007 int next[M]; char pattern[M]; void pre(int len) { int i = 0, j = -1; next[0] = -1; while(i != len) { if(j == -1 || pattern[i] == pattern[j]) next[++i] = ++j; else j = next[j]; } } int main() { //freopen("in.txt","r",stdin); while(scanf("%s",pattern)!=EOF) { if(strcmp(pattern,".")==0)break; int len=strlen(pattern); pre(len); if(len%(len-next[len])==0) printf("%d\n",len/(len-next[len])); else printf("1\n"); } return 0; }