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One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null node, 阅读全文
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Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible. Note: The l 阅读全文
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Given a sequence of n integers a1, a2, ..., an, a 132 pattern is a subsequence ai, aj, ak such that i < j < k and ai < ak < aj. Design an algorithm th 阅读全文
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You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1' 阅读全文
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Given a circular array (the next element of the last element is the first element of the array), print the Next Greater Number for every element. The 阅读全文
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Given a nested list of integers, implement an iterator to flatten it. Each element is either an integer, or a list -- whose elements may also be integ 阅读全文
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Implement the following operations of a queue using stacks. push(x) -- Push element x to the back of queue. pop() -- Removes the element from in front 阅读全文
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Implement the following operations of a stack using queues. push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack. to 阅读全文
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Implement a trie with insert, search, and startsWith methods. 题目含义：实现字典树的insert, search, 和startsWith 方法 字典树概念参考http://blog.csdn.net/u012501459/article 阅读全文
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Suppose you have N integers from 1 to N. We define a beautiful arrangement as an array that is constructed by these N numbers successfully if one of t 阅读全文
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A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59). Each LED represents 阅读全文
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Given a collection of distinct numbers, return all possible permutations. For example,[1,2,3] have the following permutations: [ [1,2,3], [1,3,2], [2, 阅读全文
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Given a list, rotate the list to the right by k places, where k is non-negative. For example:Given 1->2->3->4->5->NULL and k = 2,return 4->5->1->2->3- 阅读全文
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Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Note: Do not modify the linked list. 题目含义：判断列表是否有环路，如果 阅读全文
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Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x. You should preserve the 阅读全文
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Given a singly linked list, determine if it is a palindrome. 题目含义：给定一个单列表，判断是否构成回文 阅读全文
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Given a linked list, remove the nth node from the end of list and return its head. For example, Note:Given n will always be valid.Try to do this in on 阅读全文
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Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 题目含义：判断一个列表是否有环路 思路：参考142. Linked List C 阅读全文
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Given a string and a string dictionary, find the longest string in the dictionary that can be formed by deleting some characters of the given string. 阅读全文
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Divide two integers without using multiplication, division and mod operator. If it is overflow, return MAX_INT. 题目含义：不要使用乘 除 取模，计算除法 方法一： 阅读全文