2015 年 12月 26 日随笔档案 - neverlandly

2015年12月26日

摘要：参考了这个总结，非常详细：http://segmentfault.com/a/1190000003817671 最好方法：映射找环法复杂度时间 O(N) 空间 O(1) 思路假设数组中没有重复，那我们可以做到这么一点，就是将数组的下标和1到n每一个数一对一的映射起来。比如数组是213,则映射阅读全文

posted @ 2015-12-26 13:56 neverlandly 阅读(321) 评论(0) 推荐(0)

Leetcode: Walls and Gates

摘要： Push all gates into queue first. Then for each gate update its neighbor cells who is empty and push them to the queue. Repeating above steps until the 阅读全文

posted @ 2015-12-26 13:14 neverlandly 阅读(396) 评论(0) 推荐(0)

Leetcode: Move Zeroes

摘要：第二遍做法：双指针压缩法：O(N), 空间：O(1) 实际上就是将所有的非0数向前尽可能的压缩，最后把没压缩的那部分全置0就行了。比如103040，先压缩成134，剩余的3为全置为0。过程中需要一个指针记录压缩到的位置。 Q：如果要把所有的0放在前面而不是后面呢？A：同样的解题思路，但是是从后向前阅读全文

posted @ 2015-12-26 09:51 neverlandly 阅读(358) 评论(0) 推荐(0)

Leetcode: Peeking Iterator

摘要： My thinking is: use a double cache: long cache, when no number is cached, cache = Long.MIN_VALUE. When i call next(), it will firstly check if there's 阅读全文

posted @ 2015-12-26 09:42 neverlandly 阅读(470) 评论(0) 推荐(0)

Leetcode: Inorder Successor in BST

摘要：网上看到更好的方法：https://leetcode.com/discuss/77805/java-5ms-short-code-with-explanations The idea is to compare root's value with p's value if root is not n 阅读全文

posted @ 2015-12-26 08:49 neverlandly 阅读(391) 评论(0) 推荐(0)

Leetcode: Zigzag Iterator

摘要： Best Solution: O(N) This solution also works for K vectors Use a queue to store the iterators in different vectors. Every time we call next(), we pop 阅读全文

posted @ 2015-12-26 08:11 neverlandly 阅读(349) 评论(0) 推荐(0)

Leetcode: Wiggle Sort

摘要： Given an unsorted array nums, reorder it in-place such that nums[0] = nums[2] = nums[i - 1]如果i是偶数，nums[i] nums[i - 1]，则交换以后肯定有nums[i] =nums[i-1])) {... 阅读全文

posted @ 2015-12-26 07:38 neverlandly 阅读(300) 评论(0) 推荐(0)

Leetcode: Perfect Squares

摘要： Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n.For example, given n = 12, ... 阅读全文

posted @ 2015-12-26 04:57 neverlandly 阅读(260) 评论(0) 推荐(0)

Leetcode: First Bad Version

摘要： You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality c... 阅读全文

posted @ 2015-12-26 02:43 neverlandly 阅读(241) 评论(0) 推荐(0)

Leetcode: Find the Celebrity

摘要：最佳做法：O（N）time， O(1)space The first pass is to pick out the candidate. If candidate knows i, then switch candidate. The second pass is to check whether 阅读全文

posted @ 2015-12-26 01:46 neverlandly 阅读(378) 评论(0) 推荐(0)

Leetcode: Integer to English Words

摘要： Career Cup 150 Pg 442 Think of Convert(19,323,984) = Process(19) + "million" + Process(323) + "thousand" + Process(984) + "" The Process is a process 阅读全文

posted @ 2015-12-26 00:08 neverlandly 阅读(376) 评论(0) 推荐(0)