其实就是用一个int数组记录其中一个循环中的循环个数,
// KMP算法
#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#include<stdlib.h>
#include<cmath>
using namespace std;
char s[2000000];
int go[2000000];
int main()
{
//freopen("fuck.txt","r",stdin);
int i,j,k;
while (cin>>s)
{
if (s[0]=='.')
break;
int n=strlen(s);
go[0]=0;
j=-1; //这里注意
for (i=1;i<n;i++)
{
while (j>0&&s[j+1]!=s[i]) //循环中的一个数没有满足要求,则返回原来的满足要求的一个数.
j=-1; //或者用 j=go[j]; 其实后者不易理解,而且效率感觉 更慢,还是自己用的这个简单粗暴,
if (s[j+1]==s[i])
j++;
go[i]=j;
//cout<<go[i]<<endl;
}
if (n%(n-go[n-1]-1)==0) //这里也注意
cout<<n/(n-go[n-1]-1)<<endl;
else
cout<<'1'<<endl;
}
return 0;
}
Power Strings
Time Limit: 3000MS | | Memory Limit: 65536K |
Total Submissions: 21745 | | Accepted: 9128 |
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
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.
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