leetcode记录19. Remove Nth Node From End of List.

hinanmu

于 2019-08-24 10:28:46 发布

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本文链接：https://blog.youkuaiyun.com/csdn_47/article/details/100049794

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本文介绍了一种高效的C++算法，用于从单链表中删除倒数第N个节点。该算法在LeetCode上的RemoveNthNodeFromEndofList题目中表现优异，运行时间为4ms，内存使用为8.4MB，分别优于86.01%和100.00%的在线提交。通过双指针技巧，算法实现了对链表的有效操作。

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19. Remove Nth Node From End of List.

Runtime: 4 ms, faster than 86.01% of C++ online submissions for Remove Nth Node From End of List.
Memory Usage: 8.4 MB, less than 100.00% of C++ online submissions for Remove Nth Node From End of List.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        int num = 0;
        ListNode* l = head;
        ListNode* m = head;
        while (m != NULL)
        {
            if (num == n+1)
            {
                m = m->next;
                l = l->next;
            }
            else
            {
                num++;
                m = m->next;
            }
        }

        if (num == n)
        {
            return head->next;
        }
        else
        {
            l->next = l->next->next;
        }
        
        return head;
    }
};