[HDU 1358]Period[kmp求周期]

题意:

每一个power前缀的周期数(>1).

思路:

kmp的next. 每一个前缀都询问一遍.

#include <cstring>
#include <cstdio>
const int MAXN = 1000005;
int next[MAXN];
char s[MAXN];
//93MS	5092K
void prekmp()
{
    next[0] = -1;
    int j = -1;
    for(int i=1;s[i];i++)
    {
        while(j!=-1 && s[j+1]!=s[i])    j = next[j];
        if(s[j+1]==s[i])    j++;
        next[i] = j;
    }
}

int main()
{
    int n,cas = 0;
    while(scanf("%d",&n) && n)
    {
        scanf("%s",s);
        printf("Test case #%d
",++cas);
        prekmp();
        int len;
        for(int i=1;i<n;i++)
        {
            len = i-next[i];
            int k;
            if(!((i+1)%len))
            {
                if((k=(i+1)/len)>1)
                    printf("%d %d
",i+1,k);
            }
        }
        printf("
");
    }

}