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Sort a linked list inO(nlogn) time using constant space complexity.Merge sort先根据mid node把list 分割为 单个 node ，然后merge/** * Definition for singly-linked l... 阅读全文
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Sort a linked list using insertion sort.思路： 建立一个fake head, 依次从list中取出一个node，插入到 fake head 的list中去，从小到大排列。public class Solution { public ListNode insertionSortList(ListNode head) { ListNode prehead = new ListNode(Integer.MIN_VALUE); ListNode runner = head; while(runner != null... 阅读全文
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Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations:getandset.get(key)- Get the valu... 阅读全文
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Given a singly linked listL:L0→L1→…→Ln-1→Ln,reorder it to:L0→Ln→L1→Ln-1→L2→Ln-2→…You must do this in-place without altering the nodes' values.For exam... 阅读全文
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Given a stringsand a dictionary of wordsdict, add spaces insto construct a sentence where each word is a valid dictionary word.Return all such possible sentences.For example, givens="catsanddog",dict=["cat", "cats", "and", "sand", "dog"].A 阅读全文
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Given a stringsand a dictionary of wordsdict, determine ifscan be segmented into a space-separated sequence of one or more dictionary words.For example, givens="leetcode",dict=["leet", "code"].Return true because"leetcode"can be segmented as"leet code&quo 阅读全文
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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
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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