KMP入门（周期）

#include<iostream>
#include<cstdio>
#include<cstring>

using namespace std;

char s[1000005];
int fail[1000005];
int len;

void get_fail();

int main()
{
    while(scanf("%s",s+1),s[1]!=‘.‘)
    {
       len=strlen(s+1);
       get_fail();
       int ans=1;
       //ÀûÓÃfail[len]
       if(len%(len-fail[len])==0)
           ans=len/(len-fail[len]);
       printf("%d\n",ans);
    }
}
void get_fail()
{
    memset(fail,0,sizeof(fail));
    fail[0]=-1;
    for(int i=1;i<=len;i++)
    {
        int p=fail[i-1];
        while(p>=0&&s[p+1]!=s[i])
        p=fail[p];
        fail[i]=p+1;
        //cout<<i<<" "<<fail[i]<<endl;
    }
}