The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.)
Example 1
Input: head = [1, 2, 3, 4]
Output: [2, 1, 4, 3]
Given the head of a singly linked list, reverse the list, and return the reversed list.
Example 1
Input: head = [1, 2, 3, 4, 5]
Output: [5, 4, 3, 2, 1]
Example 2
Input: head = [1, 2]
Output: [2, 1]
Example 3
Input: head = []
Output: []
Given the head of a linked list and an integer val, remove all the nodes of the linked list that has Node.val == val, and return the new head.
Example 1
Input: head = [1, 2, 6, 3, 4, 5, 6], val = 6
Output: [1, 2, 3, 4, 5]
Example 2
Input: head = [], val = 1
Output: []
