sophie2805的专栏

原始题目如下，意为后序遍历二叉树，不要用递归。 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].

原题如下,不让用extra Given an array of integers, every element appears three times except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implem

题目如下。 You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? x

原始题目如下，意为寻找数组和最大的子串，返回这个最大和即可。 Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [−2,1,−3,4,−1,2,1,−5,4], the

原题如下，意思就是说无序数组（由0,1,2组成），一遍扫描，把数组整理成0,1,2这样的序列。 Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red,