KMP

KMP

    int i=0,j=-1;
    next1[0]=-1;
    while(i<x) //x为字符串长度
    {
        if(j==-1||k[j]==k[i])
        {
            i++;
            j++;
            next1[i]=j;
        }
        else
            j=next1[j];
    }

循环节

设字符串长度为l,l能被l-next[l]整除,循环节长度L为l-next[l],否则需要补L-l%L个字符才能循环.