每日一练 | Data Scientist & Business Analyst & Leetcode 面试题 274
自2017年6月15日起，数据应用学院与你一起温习数据科学（DS）和商业分析（BA）领域常见的面试问题。从2017年10月4号起，每天再为大家分享一道Leetcode算法题。
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DS Interview Questions
How will you define the number of clusters in a clustering algorithm?
BA Interview Questions
If Company ADG had $500,000 MRR at the beginning of the month, $450,000 MRR at the end of the month, and $65,000 MRR in upgrades that month from existing customers, what is the revenue churn rate?
Leetcode Questions
Description:
A peak element is an element that is greater than its neighbors.
Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.
The array may contain multiple peaks, in that case return the index to any one of the peaks is fine.
Input: [1, 2, 3, 1]
Output: 2
Assumptions:
You may imagine that num[-1] = num[n] = -∞.
欲知答案如何？请见下期分解！
Day 173 答案揭晓
DS Interview Questions
In any 15-minute interval, there is a 20% probability that you will see at least one shooting star. What is the probability that you see at least one shooting star in the period of an hour?
Probability of not seeing any shooting star in 15 minutes is
= 1 – P( Seeing one shooting star )
= 1 – 0.2 = 0.8
Probability of not seeing any shooting star in the period of one hour
= (0.8) ^ 4 = 0.4096
Probability of seeing at least one shooting star in the one hour
= 1 – P( Not seeing any star )
= 1 – 0.4096 = 0.5904
BA Interview Questions
If Company ADG had 500 customers at the beginning of the month and only 450 customers at the end of the month, what is the customer churn rate?
Customer Churn Rate
= (Customers beginning of month – Customers end of month) / Customers beginning of month
= (500-450)/500
= 10%
Leetcode Questions
Description:
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Input: “A man, a plan, a canal: Panama”
Output: true
Time Complexity: O(n)
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