Leetcode - 随笔分类(第18页) - neverlandly

Leetcode: Smallest Rectangle Enclosing Black Pixels

摘要：An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one bla 阅读全文

posted @ 2015-12-29 08:28 neverlandly 阅读(942) 评论(0) 推荐(0)

Leetcode: Longest Increasing Subsequence

摘要：讲解一：用一个数组来存 the smallest tail of all increasing subsequences with length i+1 in tails[i]. For example, say we have nums = [4,5,6,3], then all the ava 阅读全文

posted @ 2015-12-29 06:07 neverlandly 阅读(429) 评论(0) 推荐(0)

Leetcode: Bulls and Cows

摘要：Be careful, when calculate B, you should exclude A's cases 阅读全文

posted @ 2015-12-29 04:52 neverlandly 阅读(338) 评论(0) 推荐(0)

Leetcode: Serialize and Deserialize Binary Tree

摘要：Referring this post: https://leetcode.com/problems/serialize-and-deserialize-binary-tree/discuss/74253/Easy-to-understand-Java-Solution But instead us 阅读全文

posted @ 2015-12-29 03:16 neverlandly 阅读(378) 评论(0) 推荐(0)

Leetcode: Binary Tree Longest Consecutive Sequence

摘要：递归法复杂度时间O(n) 空间O(h) 思路因为要找最长的连续路径，我们在遍历树的时候需要两个信息，一是目前连起来的路径（curLen）有多长（以当前节点为终点），二是目前路径的上一个节点的值(preVal)。每一次递归，先检查当前节点是否比上一节点大1, 是，curLen++, 否curL 阅读全文

posted @ 2015-12-29 01:11 neverlandly 阅读(364) 评论(0) 推荐(0)

Leetcode: Best Meeting Point

摘要：A group of two or more people wants to meet and minimize the total travel distance. You are given a 2D grid of values 0 or 1, where each 1 marks the h... 阅读全文

posted @ 2015-12-28 12:06 neverlandly 阅读(291) 评论(0) 推荐(0)

Leetcode: Find Median from Data Stream

摘要：最大最小堆复杂度时间 O(logN) insert, O(1) query, 空间 O(N) 思路维护一个最大堆，一个最小堆。最大堆存的是到目前为止较小的那一半数，最小堆存的是到目前为止较大的那一半数，这样中位数只有可能是堆顶或者堆顶两个数的均值。而维护两个堆的技巧在于判断堆顶数和新来的数的大阅读全文

posted @ 2015-12-28 07:45 neverlandly 阅读(282) 评论(0) 推荐(0)

Leetcode: Flip Game II

摘要：You are playing the following Flip Game with your friend: Given a string that contains only these two characters: + and -, you and your friend take tu 阅读全文

posted @ 2015-12-28 06:05 neverlandly 阅读(541) 评论(0) 推荐(0)

Leetcode: Flip Game

摘要：You are playing the following Flip Game with your friend: Given a string that contains only these two characters: + and -, you and your friend take tu... 阅读全文

posted @ 2015-12-28 04:17 neverlandly 阅读(306) 评论(0) 推荐(0)

Leetcode: Nim Game

摘要：You 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 ston... 阅读全文

posted @ 2015-12-28 02:17 neverlandly 阅读(227) 评论(0) 推荐(0)

Leetcode: Word Pattern II

摘要：Given a pattern and a string str, find if str follows the same pattern.Here follow means a full match, such that there is a bijection between a letter... 阅读全文

posted @ 2015-12-28 01:45 neverlandly 阅读(345) 评论(0) 推荐(0)

Leetcode: Word Pattern

摘要：Given a pattern and a string str, find if str follows the same pattern. Here follow means a full match, such that there is a bijection between a lette 阅读全文

posted @ 2015-12-28 00:54 neverlandly 阅读(330) 评论(0) 推荐(0)

Leetcode: Game of Life

摘要：编解码法复杂度时间 O(NN) 空间 O(1) 思路最简单的方法是再建一个矩阵保存，不过当inplace解时，如果我们直接根据每个点周围的存活数量来修改当前值，由于矩阵是顺序遍历的，这样会影响到下一个点的计算。如何在修改值的同时又保证下一个点的计算不会被影响呢？实际上我们只要将值稍作编码就行了阅读全文

posted @ 2015-12-27 13:18 neverlandly 阅读(510) 评论(0) 推荐(0)

Leetcode: Alien Dictionary && Summary: Topological Sort

摘要：There is a new alien language which uses the latin alphabet. However, the order among letters are unknown to you. You receive a list of words from the... 阅读全文

posted @ 2015-12-27 12:05 neverlandly 阅读(575) 评论(0) 推荐(0)

Leetcode: Unique Word Abbreviation

摘要：An abbreviation of a word follows the form . Below are some examples of word abbreviations:a) it --> it (no abbreviation) ... 阅读全文

posted @ 2015-12-27 07:14 neverlandly 阅读(383) 评论(0) 推荐(0)

Leetcode: Find the Duplicate Number

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(325) 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(401) 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(360) 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(471) 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(392) 评论(0) 推荐(0)

随笔分类 - Leetcode