摘要：
A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.Return a deep copy of the list.Ref:http://fisherlei.blogspot.com/2013/11/leetcode-copy-list-with-random-pointer.html如图分三步：http://lh6.ggpht.com/-xlfWkNgeNhI/Uomwl3lB47I/A 阅读全文
摘要：
Given a linked list, return the node where the cycle begins. If there is no cycle, returnnull.Follow up:Can you solve it without using extra space?解题思路：双指针， 一个指针一次走一步，一个指针一次走两步， 如果有环，定相遇。然后将快指针移到头部，再一次走一步，当两只真再次相遇的时候就是指针的头/** * Definition for singly-linked list. * class ListNode { * int val; * ... 阅读全文
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Given an array of integers, every element appearstwiceexcept for one. Find that single one.Could you implement it without using extra memory?Ref:http://www.cnblogs.com/feiling/p/3349654.html[解题思路]以前看书时遇到过，一个数组中有一个元素出现一次，其他每个元素都出现两次要求空间复杂度为O(1)由于两个相同的元素异或的结果为0,而0^a==a，将数组中所有元素都进行异或，得到结果就是只出现一次的元素publ 阅读全文
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There areNchildren standing in a line. Each child is assigned a rating value.You are giving candies to these children subjected to the following requi... 阅读全文
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There areNgas stations along a circular route, where the amount of gas at stationiisgas[i].You have a car with an unlimited gas tank and it costscost[... 阅读全文
摘要：
Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?两个指针，一个一次走两步，一个一次走一步，相遇说明有环/** * Definition for singly-linked list. * class ListNode { * int val; * ListNode next; * ListNode(int x) { * val = x; * next = null; * ... 阅读全文
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Clone an undirected graph. Each node in the graph contains alabeland a list of itsneighbors.OJ's undirected graph serialization:Nodes are labeled uniquely.We use#as a separator for each node, and,as a separator for node label and each neighbor of the node.As an example, consider the serialized g 阅读全文