You are given the head of a singly linked list. The goal is to reorder the list such that the nodes are arranged as follows: L0 → Ln → L1 → Ln-1 → L2 → Ln-2 → …, without modifying the values of the nodes. Only the structure of the list can be changed.
Design and implement an LRU (Least Recently Used) cache. The cache should support two operations: get(key) and put(key, value). Both operations must run in O(1) time on average. If the cache exceeds its capacity, the least recently used key should be evicted.
Given the head of a singly linked list, reverse the list and return the new head of the reversed list. You need to reverse the order of the nodes in the list such that the first node becomes the last, the second becomes the second to last, and so on.
You are given a node in a singly linked list, and you are asked to delete this node from the list. The node is guaranteed to be not the last node in the list. After the deletion, the values before the node should remain in the same order, and the values after the node should also remain in the same order.
You are given the head of a singly linked list. Your task is to reorder the list such that all nodes at odd indices are grouped together followed by all nodes at even indices. The first node is considered to have an odd index, the second node is considered to have an even index, and so on. The relative order inside the odd and even groups should remain unchanged.
