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1. Problem DescriptionGiven inorder and postorder traversal of a tree, construct the binary tree. 2. My solution类似的题目还有105，是根据中序和前序重构二叉树。根据前序和后序是无法重构二叉树的，因为重构二叉树需要中序遍历顺序提供划分左右子树的方法。 Findro

转载自hackbuteer1Catalan数——卡特兰数今天阿里淘宝笔试中碰到两道组合数学题，感觉非常亲切，但是笔试中失踪推导不出来后来查了下，原来是Catalan数。悲剧啊，现在整理一下一、Catalan数的定义令h(1)=1，Catalan数满足递归式：h(n) = h(1)*h(n-1) + h(2)*h(n-2) + ... + h(n-1)h(1)，n>=

1.区间DP入门 —— POJ 2955 括号匹配我们先看一道经典题目：给出一个字符串，仅含()[]四个字符，问整个字符串里最多有多少个匹配的括号。Sample Input((()))()()()([]]))[)(([][][)endSample Output66406 2. My solution of POJ 2955区间dp

1. Problem DescriptionGiven a positive integer n, break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get. For

1. Problem DescriptionGiven a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.2. My solution

1. Problem DescriptionInvert a binary tree.      4   /   \  2     7 / \     / \1   3  6  9 to     4   /   \  7     2 / \     / \9   6  3  1 Trivia:This problem was in

1. Problem DescriptionGiven an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed

1. Problem Description Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.For example:Given num = 38, the process is like: 3 + 8 = 11, 1

1. Problem DescriptionCalculate the sum of two integers a and b, but you are not allowed to use the operator + and -. Example:Given a = 1 and b = 2, return 3. 什么？你说好简单？输出两个数的和？ 2. My s

1. Problem DescriptionThere are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if

1. Problem DescriptionYou are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 stones. The one who removes th

1. Problem DescriptionWrite a function that takes a string as input and returns the string reversed. Example:Given s = "hello", return "olleh".反转字符串2. My solution1（另开辟字符串存储）class Solutio

1. Problem DescriptionGiven a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only mov

1. Problem DescriptionGiven an integer array nums, find the sum of the elements between indices i and j (i≤ j), inclusive. The update(i, val) function modifies nums by updating the element at

1. Problem Description of 53.Maximum SubarrayFind 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. Problem DescriptionGiven two arrays, write a function to compute their intersection. Example:Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2]. Note:Each element in the result mu

1. Problem DescriptionSuppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. You may assum

1. Problem DescriptionDesign a data structure that supports all following operations in average O(1) time. insert(val): Inserts an item val to the set if not already present.remove(val): Remov

1. Problem DescriptionA peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element and return its index. The array may c

1. Problem DescriptionGiven an index k, return the kth row of the Pascal's triangle. For example, given k = 3,Return [1,3,3,1]. Note:Could you optimize your algorithm to use only O(k) ex

1. Problem DescriptionSay you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell

1. Problem DescriptionGiven an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements. For example, given nums = [0, 1, 0, 3,

1. Problem DescriptionGiven numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5,Return [     [1],    [1,1],   [1,2,1],  [1,3,3,1], [1,4,6,4,1

1. Problem DescriptionGiven a sorted array, remove the duplicates in place such that each element appear only once and return the new length. Do not allocate extra space for another array, you m

1.7.1 Problem DescriptionGiven an array of size n, find the majority element. The majority element is the element that appears more than⌊ n/2 ⌋ times.You may assume that the array is non-empty

1. Problem DescriptionGiven a non-negative number represented as an array of digits, plus one to the number. The digits are stored such that the most significant digit is at the head of the list

1. Problem DescriptionGiven two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note:You may assume that nums1 has enough space (size that is greater or equa

1. Problem DescriptionRotate an array of n elements to the right by k steps. For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4]. Note:Try to come up

1. Problem DescriptionGiven an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between i and j

1.Problem Description 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 exactly one solution.

1.Problem descriptionGiven an array and a value, remove all instances of that value in place and return the new length. Do not allocate extra space for another array, you must do this in place w