Hygeia

摘要： In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this n 阅读全文

摘要： In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (wi 阅读全文

摘要： Two elements of a binary search tree (BST) are swapped by mistake. Recover the tree without changing its structure. Example 1: Example 2: This questio 阅读全文

摘要： Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) -- Push element x onto stack. pop() -- Remov 阅读全文

摘要： REFERENCE: https://blog.csdn.net/fuxuemingzhu/article/details/70241424 Given a binary tree, flatten it to a linked list in-place. For example, given t 阅读全文

摘要： A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null. Return a deep copy 阅读全文

摘要： Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any 阅读全文

摘要： A sequence of number is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the 阅读全文

摘要： Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1. Example 1: Example 2: Example 3 阅读全文

摘要： Every email consists of a local name and a domain name, separated by the @ sign. For example, in alice@leetcode.com, alice is the local name, and leet 阅读全文