61.旋转链表

两天宇宙人

2020-02-19

👺

连成环，然后改变头部位置。

class Solution {
public:
    ListNode* rotateRight(ListNode* head, int k) {
        if(!head || !head->next) return head;
        int count = 0;
        auto h = head;
        while(h->next) {
            h = h->next;
            ++count;
        }
        ++count;
        // cout << count << endl;
        h->next = head;
        k = k % count;
        auto new_tail = head;
        int move = count - k;
        // cout << move << endl;
        for(; move > 0 ; --move) {
            if(move == 1) {
                auto nx = new_tail->next;
                new_tail->next = nullptr;
                new_tail = nx;
            } else 
                new_tail = new_tail->next;
        }
        return new_tail;
    }
};