LeetCode-25 K个一组反转链表

LeetCode-25 K个一组反转链表

1:52:03

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @param {number} k
 * @return {ListNode}
 */
var reverseKGroup = function(head, k) {
    if(!head)return null;
    let ret=new ListNode(-1,head),pre=ret;
    do{
        pre.next=reverse(pre.next,k);
        for(let i=0;i<k&&pre;i++){
            pre=pre.next;
        }
        if(!pre) break;
    }while(1);
    return ret.next;
};
var reverse=function(head,n){
    let pre=head,cur=head,con=n;
    while(--n&&pre){
        pre=pre.next;
    }
    if(!pre) return head;
    pre=null;
    while(con--){
        [cur.next,pre,cur]=[pre,cur,cur.next];
    }
    head.next=cur;
    return pre;
}

---