Weekly #11
@Date : 2019-06-10 09:11:00
@Author : Lewis Tian (taseikyo@gmail.com)
@Link : https://taseikyo.github.io
@Range : 2019/06/10 - 2019/06/16
Photo by Pavel Brodsky on Unsplash
Table of Contents
algorithm
347. Top K Frequent Elements
Given a non-empty array of integers, return the k most frequent elements.
Example 1:
Input: nums = [1,1,1,2,2,3], k = 2
Output: [1,2]
Example 2:
Input: nums = [1], k = 1
Output: [1]
Note:
- You may assume k is always valid, 1 ≤ k ≤ number of unique elements.
- Your algorithm's time complexity must be better than O(n log n), where n is the array's size.
solution
I think using Python is just cheating. Just one linehttps://github.com/taseikyo/arts/blob/master.
def topKFrequent(self, nums: List[int], k: int) -> List[int]:
return [key for key, value in Counter(nums).most_common(k)]
448. Find All Numbers Disappeared in an Array
Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.
Find all the elements of [1, n] inclusive that do not appear in this array.
Could you do it without extra space and in O(n) runtime? You may assume the returned list does not count as extra space.
Example:
Input:
[4,3,2,7,8,2,3,1]
Output:
[5,6]
solution
One line Python cheating
def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
return list((set(range(1, len(nums) + 1))) - (set(nums)))
538. Convert BST to Greater Tree
Given a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus sum of all keys greater than the original key in BST.
Example:
Input: The root of a Binary Search Tree like this:
5
/ \
2 13
Output: The root of a Greater Tree like this:
18
/ \
20 13
solution
preorder (right child node first) traversal
review
This article describes several paging mechanisms in x86 and x64.
tip
share
- A Virtual Machine Introspection Triggering Mechanism Based on VMFUNC
I found this paper when I googled VMFUNC keyword.
This paper proposes a VMFUNC based VM introspection mechanism, which avoids the system pause and minimizes the overhead of VM exits.