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摘要： Given a binary tree, return the postorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [3,2,1]. Note: Re 阅读全文

摘要： Given a binary tree, return the preorder traversal of its nodes' values. Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive soluti 阅读全文

摘要： Sort a linked list using insertion sort. 写的思路其实很朴素： 1.先将原链表一个结点摘下来。 2.插入到有序的新链表里的合适位置。 3.循环1、2步骤，直到原链表所有结点遍历完毕。 时间复杂度为O(n2)，空间复杂度为O(1)。 阅读全文

摘要： Sort a linked list in O(n log n) time using constant space complexity. 利用归并排序的思想，递归合并两个有序的链表。 首先将链表递归分成两部分，直到只有一个结点为止，然后从底到上合并链表。 当然是学习大牛代码后写出的，如下： 阅读全文

摘要： leetcode-149-Max Points on a Line 阅读全文

摘要： Given an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime comple 阅读全文

摘要： You are given two non - empty linked lists representing two non - negative integers. The digits are stored in reverse order and each of their nodes co 阅读全文

摘要： Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, /. Each operand may be an integer or another e 阅读全文

摘要： Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have ex 阅读全文

摘要： 求二叉树最小深度 阅读全文