04 2014 档案

动态规划小结 - 一维动态规划 - 时间复杂度 O(n)，题 [LeetCode] Jump Game，Decode Ways
摘要：引言一维动态规划根据转移方程，复杂度一般有两种情况。func(i) 只和 func(i-1)有关，时间复杂度是O(n)，这种情况下空间复杂度往往可以优化为O(1)func(i) 和 func(1~i-1)有关，时间复杂度是O(n*n)，这种情况下空间复杂度一般无法优化，依然为O(n)本篇讨论第一种情... 阅读全文

posted @ 2014-04-28 06:35 Felix Fang 阅读(8306) 评论(0) 推荐(0)

[LeetCode] Merge Interval系列，题：Insert Interval，Merge Intervals
摘要：Interval的合并时比较常见的一类题目，网上的Amazon面经上也有面试这道题的记录。这里以LeetCode上的例题做练习。Merge IntervalsGiven a collection of intervals, merge all overlapping intervals.For ex... 阅读全文

posted @ 2014-04-27 06:08 Felix Fang 阅读(606) 评论(0) 推荐(0)

[LeetCode] Simplify Path，文件路径简化，用栈来做
摘要：Given an absolute path for a file (Unix-style), simplify it.For example,path="/home/", =>"/home"path="/a/./b/../../c/", =>"/c"click to show corner cas... 阅读全文

posted @ 2014-04-23 04:23 Felix Fang 阅读(444) 评论(0) 推荐(0)

[LeetCode] Sort Colors 对于元素取值有限的数组，只遍历一遍的排序方法
摘要：Given an array withnobjects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, wh... 阅读全文

posted @ 2014-04-22 11:10 Felix Fang 阅读(3625) 评论(0) 推荐(0)

[LeetCode] Largest Rectangle in Histogram O(n) 解法详析， Maximal Rectangle
摘要：Largest Rectangle in HistogramGivennnon-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of l... 阅读全文

posted @ 2014-04-20 13:06 Felix Fang 阅读(12413) 评论(3) 推荐(0)

[线索二叉树] [LeetCode] 不需要栈或者别的辅助空间，完成二叉树的中序遍历。题：Recover Binary Search Tree，Binary Tree Inorder Traversal
摘要：既上篇关于二叉搜索树的文章后，这篇文章介绍一种针对二叉树的新的中序遍历方式，它的特点是不需要递归或者使用栈，而是纯粹使用循环的方式，完成中序遍历。线索二叉树介绍首先我们引入“线索二叉树”的概念："A binary tree isthreadedby making all right child po... 阅读全文

posted @ 2014-04-16 01:05 Felix Fang 阅读(1434) 评论(0) 推荐(0)

二叉树系列 - 二叉搜索树 - [LeetCode] 中序遍历中利用 pre节点避免额外空间。题：Recover Binary Search Tree，Validate Binary Search Tree
摘要：二叉搜索树是常用的概念，它的定义如下：The left subtree of a node contains only nodes with keysless thanthe node's key.The right subtree of a node contains only nodes wit... 阅读全文

posted @ 2014-04-16 00:39 Felix Fang 阅读(1552) 评论(0) 推荐(0)

二叉树系列 - [LeetCode] Symmetric Tree 判断二叉树是否对称，递归和非递归实现
摘要：Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric: 1 / \ ... 阅读全文

posted @ 2014-04-09 11:26 Felix Fang 阅读(7026) 评论(1) 推荐(0)

[LeetCode] Binary Tree Level Order Traversal 与 Binary Tree Zigzag Level Order Traversal，两种按层次遍历树的方式，分别两个队列，两个栈实现
摘要：Binary Tree Level Order TraversalGiven a binary tree, return thelevel ordertraversal of its nodes' values. (ie, from left to right, level by level).Fo... 阅读全文

posted @ 2014-04-08 11:51 Felix Fang 阅读(710) 评论(0) 推荐(0)

动态规划小结 - 二维动态规划 - 时间复杂度 O(n*n)的棋盘型，题 [LeetCode] Minimum Path Sum，Unique Paths II，Edit Distance
摘要：引言二维动态规划中最常见的是棋盘型二维动态规划。即func(i, j) 往往只和 func(i-1, j-1), func(i-1, j) 以及 func(i, j-1) 有关这种情况下，时间复杂度 O(n*n)，空间复杂度往往可以优化为O(n)例题 1Minimum Path SumGiven a... 阅读全文

posted @ 2014-04-06 06:58 Felix Fang 阅读(5018) 评论(0) 推荐(0)

[LeetCode] Populating Next Right Pointers in Each Node I, II
摘要：题目：Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate each next poi... 阅读全文

posted @ 2014-04-06 05:37 Felix Fang 阅读(6430) 评论(0) 推荐(0)

[LeetCode] 递推思想的美妙 Best Time to Buy and Sell Stock I, II, III O(n) 解法
摘要：题记：在求最大最小值的类似题目中，递推思想的奇妙之处，在于递推过程也就是比较求值的过程，从而做到一次遍历得到结果。LeetCode 上面的这三道题最能展现递推思想的美丽之处了。题1 Best Time to Buy and Sell StockSay you have an array for wh... 阅读全文

posted @ 2014-04-04 11:28 Felix Fang 阅读(1075) 评论(0) 推荐(0)

二叉树系列 - 二叉树里的最长路径 例 [LeetCode] Binary Tree Maximum Path Sum
摘要：题目：Binary Tree Maximum Path SumGiven a binary tree, find the maximum path sum.The path may start and end at any node in the tree.For example:Given the... 阅读全文

posted @ 2014-04-01 11:59 Felix Fang 阅读(10910) 评论(0) 推荐(0)

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