Given a string s and a dictionary of words wordDict, return true if s can be segmented into a space-separated sequence of one or more words from the dictionary. The same word in the dictionary can be reused multiple times.
Given the head of a linked list, find the node where the cycle begins. If no cycle exists, return null. The list may contain a cycle, which occurs if a node can be revisited by following the ’next’ pointers continuously.
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.
You are given an array of strings tokens that represents an arithmetic expression in Reverse Polish Notation (RPN). Your task is to evaluate the expression and return the result as an integer.
