Today I have done leetcode's March LeetCoding Challenge with cpp.

March LeetCoding Challenge 3

Description

Remove Nth Node From End of List

Given the head of a linked list, remove the nth node from the end of the list and return its head.

Example 1:

Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]

Example 2:

Input: head = [1], n = 1
Output: []

Example 3:

Input: head = [1,2], n = 1
Output: [1]

Constraints:

• The number of nodes in the list is sz.
• 1 <= sz <= 30
• 0 <= Node.val <= 100
• 1 <= n <= sz

Follow up: Could you do this in one pass?

Solution

class Solution {
public:
  ListNode* removeNthFromEnd(ListNode* head, int n) {
    ListNode *newHead = new ListNode(-1, head);
    ListNode *tail = newHead;
    ListNode *del = newHead;
    while(n--) tail = tail->next;
    while(tail->next) {
      tail = tail->next;
      del = del->next;
    }
    del->next = del->next->next;
    return newHead->next;
  }
};

// Accepted
// 208/208 cases passed (3 ms)
// Your runtime beats 64.94 % of cpp submissions
// Your memory usage beats 45.9 % of cpp submissions (13.3 MB)