LeetCode 19. Remove Nth Node From End of List

Problem: - https://leetcode.com/problems/remove-nth-node-from-end-of-list/

Solution:

	/**
	* 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) {
	auto fast = head;
	auto slow = head;
	// fast: move n step
	while(n){
	fast = fast->next;
	n--;
	}
	// if reaches the tail, remove head
	if(!fast){
	head = head->next;
	return head;
	}
	// move fast to tail
	while(fast->next){
	fast = fast->next;
	slow = slow->next;
	}
	// remove
	slow->next = slow->next->next;
	return head;
	}
	};

view raw 19-Remove-Nth-Node-From-End-of-List.cpp hosted with ❤ by GitHub