leetcode url

Solutions

To reverse a linked list, we provides recusive and non reusive way to do this.

1 -> 2 -> 3 -> 4 -> ... -> N

now, we need to swap the arrow like this:

1 <- 2 <- 3 <- 4 <- ... <- N

first round:

1. prev = nullptr, head = 1, next = 2

ListNode *reverseList(ListNode *head) {
	if (head == nullptr) {
		return nullptr;
	}
	if (head->next == nullptr) {
		return head;
	}
	ListNode *prev = nullptr;
	ListNode *curr = head;
	ListNode *next = nullptr;
	while (curr) {
		next = curr->next;
		curr->next = prev;
		prev = curr;
		curr = next;
	}
	return prev;
}

date: 2025-05-22
tags:

• leetcode/linked-list
  status: Easy

leetcode url

Solutions