[HDU 3746]Cyclic Nacklace[kmp求周期]

题意:

求从末端补足至少两周期的最小项数.

思路:

kmp求循环周期应用

#include <cstring>
#include <cstdio>
const int MAXN = 100005;
int next[MAXN];
char s[MAXN];
//125MS   688K
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 T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%s",s);
        prekmp();
        int n,len,r,q,add;
        n = strlen(s);
        len = n - 1 - next[n-1];
        r = n % len;
        q = n / len;
        if(q==1)
        {
            add = 2*len - n;
        }
        else
        {
            add = (len - r)%len;
        }
        printf("%d\n",add);
    }

}