#链表 #删除链表的倒数第N个节点

remove-nth-node-from-end-of-list.cpp

/**
 * 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* removeNthFromEnd(ListNode* head, int n) {
        ListNode* dummy = new ListNode(0);
        dummy->next = head;
      
        // [head, cur node] 区间有 n 个node
        ListNode* cur = dummy; 
        for (int i = 0; i < n; ++i) {
            cur = cur->next;
        }

        // [candidate, cur] 区间有 n+1 个node
        ListNode* candidate = dummy;
        while (cur->next != NULL) {
            cur = cur->next;
            candidate = candidate->next;
        }

        candidate->next = candidate->next->next;
        // delete candidate->next;

        return dummy->next;
    }
};