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题目 Given two integers n and k, return all possible combinations of k numbers out of the range [1, n]. You may return the answer in any order. Example 阅读全文
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题目 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] Ex 阅读全文
摘要：
题目 You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following de 阅读全文