LeetCode 61. 旋转链表

旋转链表

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* rotateRight(ListNode* head, int k) {
        if(!head) return nullptr;
        int len = 0;
        ListNode *cur = head, *tail = cur;
        while(cur != nullptr){
            if(cur->next == nullptr) tail = cur;
            cur = cur->next;
            len++;
        }
        k = k%len;
        if(!k) return head;
        cur = head;
        ListNode* pre = nullptr;
        for(int i=0;i<len-k;i++){
            pre = cur;
            cur = cur->next;
        }
        pre->next = nullptr;
        tail->next = head;
        return cur;
    }
};