davidnyc

摘要： When you start JVM you define how much RAM it can use use for processing. JVM divides this into certain memory locations for its processing purpose, t 阅读全文

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摘要： heapify unsorted array: n*logn -> o(n): 最贵的 o(logn) 操作集中在少数几个node 上 但heapify 并不是 sort, 左右并没有排序，如果需要排序的话，需要先heapify 然后再 一个一个的poll 时间复杂度是 on + onlogn = 阅读全文

摘要： 这道题首先要明确题目背景 二叉搜索树。也正是因为是二叉搜索树，所以我们可以利用二叉搜索树从小到大排好序的特性来做。 对于一个root和另外两个Node来说，它们的值会有以下几种情况： 1. root.val < p.val && root.val < q.val 此时，两个node的值都比root大 阅读全文

摘要： https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree/description/Given an array where elements are sorted in ascending order, convert it to a height balanced BST.For this problem, ... 阅读全文

摘要： https://leetcode.com/problems/validate-binary-search-tree/description/Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a ... 阅读全文

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摘要： https://leetcode.com/problems/binary-tree-longest-consecutive-sequence/description/Given a binary tree, find the length of the longest consecutive sequence path.The path refers to any sequence of node... 阅读全文

摘要： https://leetcode.com/problems/path-sum-ii/description/Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.For example:Given the below binary tree and ... 阅读全文

摘要： https://leetcode.com/problems/symmetric-tree/description/Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree [1,2,2,3,4,4,3] is ... 阅读全文