Leetcode - 随笔分类(第21页) - neverlandly

Leetcode: Sliding Window Maximum

摘要：方法一：Heap时间 O(NlogK) 空间 O(K) maintain a maximum heap, notice PriorityQueue.remove(object o) can remove certain object from our heap. When writting Maxi 阅读全文

posted @ 2015-12-20 12:25 neverlandly 阅读(422) 评论(0) 推荐(0)

Leetcode: Product of Array Except Self

摘要：Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except ... 阅读全文

posted @ 2015-12-20 11:38 neverlandly 阅读(280) 评论(0) 推荐(0)

Leetcode: Delete Node in a Linked List

摘要：Write a function to delete a node (except the tail) in a singly linked list, given only access to that node. Supposed the linked list is 1 -> 2 -> 3 - 阅读全文

posted @ 2015-12-20 08:16 neverlandly 阅读(227) 评论(0) 推荐(0)

Leetcode: Lowest Common Ancestor of a Binary Tree

摘要：Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.According to the definition of LCA on Wikipedia: “The lowest... 阅读全文

posted @ 2015-12-20 08:08 neverlandly 阅读(268) 评论(0) 推荐(0)

Leetcode: Lowest Common Ancestor of a Binary Search Tree

摘要：Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikipedia 阅读全文

posted @ 2015-12-20 08:06 neverlandly 阅读(285) 评论(0) 推荐(0)

Leetcode: Palindrome Linked List

摘要：Given a singly linked list, determine if it is a palindrome.Follow up:Could you do it in O(n) time and O(1) space?先分成大小相同(可能长度差1) 两部分, reverse一个list. ... 阅读全文

posted @ 2015-12-20 07:12 neverlandly 阅读(286) 评论(0) 推荐(0)

Leetcode: Number of Digit One

摘要：Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.For example:Given n = 13,Return 6... 阅读全文

posted @ 2015-12-20 05:21 neverlandly 阅读(259) 评论(0) 推荐(0)

Leetcode: Power of Two

摘要：Best Solution 还是有一个地方不小心：Integer.MIN_VALUE, 应该是false，但是因为只有一个1，我曾经判断为true。事实上，所有negative value都应该是false 一旦符号位为1，就return false，检查其他位只有1个1 做的时候遇到很多语法错误阅读全文

posted @ 2015-12-20 04:28 neverlandly 阅读(217) 评论(0) 推荐(0)

Leetcode: Implement Queue using Stacks

摘要：Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front o... 阅读全文

posted @ 2015-12-20 02:20 neverlandly 阅读(275) 评论(0) 推荐(0)

Leetcode: Majority Element II

摘要：Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times. The algorithm should run in linear time and in O(1) space.Hin... 阅读全文

posted @ 2015-12-20 02:02 neverlandly 阅读(316) 评论(0) 推荐(0)

Leetcode: Summary Ranges

摘要：这种题就是要写的clean and tidy，好方法：维护两个指针的方法：阅读全文

posted @ 2015-12-19 13:33 neverlandly 阅读(267) 评论(0) 推荐(0)

Leetcode: Kth Smallest Element in a BST

摘要：Java Solution 1 - Inorder Traversal We can inorder traverse the tree and get the kth smallest element. Time is O(n). Recursion method: Java Solution 2 阅读全文

posted @ 2015-12-19 13:06 neverlandly 阅读(411) 评论(0) 推荐(0)

Leetcode: Basic Calculator II

摘要：用Stack来做：时间 O(N) 空间 O(N) 因为乘法和除法不仅要知道下一个数，也要知道上一个数。所以我们用一个栈把上次的数存起来，遇到加减法就直接将数字压入栈中，遇到乘除法就把栈顶拿出来乘或除一下新数，再压回去。最后我们把栈里所有数加起来就行了。上面这段code可以先用String.repl 阅读全文

posted @ 2015-12-19 12:31 neverlandly 阅读(311) 评论(0) 推荐(0)

Leetcode: Basic Calculator

摘要：https://discuss.leetcode.com/topic/15816/iterative-java-solution-with-stack 第二遍做法：遇到digit直接走到末尾，并且直接利用sign进行计算，这样比较方便第一遍做法：阅读全文

posted @ 2015-12-19 06:12 neverlandly 阅读(371) 评论(0) 推荐(0)

Leetcode: Count Complete Tree Nodes

摘要：递归树高法复杂度时间 O(N) 空间 O(1) 思路完全二叉树的一个性质是，如果左子树最左边的深度，等于右子树最右边的深度，说明这个二叉树是满的，即最后一层也是满的，则以该节点为根的树其节点一共有2^h-1个。如果不等于，则是左子树的节点数，加上右子树的节点数，加上自身这一个。注意这里在左阅读全文

posted @ 2015-12-19 02:30 neverlandly 阅读(332) 评论(0) 推荐(0)

Leetcode: Implement Stack using Queues

摘要：Implement the following operations of a stack using queues. push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack. to 阅读全文

posted @ 2015-12-19 01:31 neverlandly 阅读(268) 评论(0) 推荐(0)

Leetcode: Maximal Square

摘要：dp问题，用一个dp[i][j]保存matrix[i][j]作为右下节点的时候的最大矩形的边长 if (matrix[i][j] == '0') dp[i][j] = 0; else dp[i][j] = min(dp[i-1][j-1], dp[i-1][j], dp[i][j-1]) + 1; 阅读全文

posted @ 2015-12-19 00:47 neverlandly 阅读(346) 评论(0) 推荐(0)

Leetcode: Contains Duplicate III

摘要：暴力枚举会LTE，解题思路是用sortedSet来解决，sortedSet可以返回一个在某个范围的subSet，同时判断这个subSet是否为空即可解决，主要，本题需要使用long类型！时间 O(NlogK) 空间 O(K) 思路要求判断之前是否存在差值小于t的数字，我们需要知道在当前数字x两边阅读全文

posted @ 2015-12-18 23:31 neverlandly 阅读(269) 评论(0) 推荐(0)

Leetcode: Invert Binary Tree

摘要：nvert a binary tree. 4 / \ 2 7 / \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1Trivia:This problem was inspired by this... 阅读全文

posted @ 2015-12-18 13:14 neverlandly 阅读(287) 评论(0) 推荐(0)

Leetcode: The Skyline Problem

摘要：参考了http://www.cnblogs.com/tonyluis/p/4564617.html 复杂度 Time Complexity is O(n^2) because removal in a PQ is O(n), 空间 O(N) I think if replace PQ with Tr 阅读全文

posted @ 2015-12-18 12:27 neverlandly 阅读(268) 评论(0) 推荐(0)

随笔分类 - Leetcode