LeetCode 206. Reverse Linked List

https://leetcode.com/problems/reverse-linked-list/ Problem

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* recursive(ListNode* cur, ListNode* prev){
	if(!cur) return prev;
	auto tmp = cur->next;
	cur->next = prev;
	return recursive(tmp, cur);
	}
	ListNode* reverseList(ListNode* head) {
	// new tail pointer
	ListNode* prev = NULL;
	// iterative pointer
	ListNode* cur = head;
	// iterative
	// while (cur) {
	// auto n = cur->next;
	// cur->next = prev;
	// prev = cur;
	// cur = n;
	// }
	// return prev
	// recursive
	return recursive(cur, prev);
	}
	};

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