每日一练 | Data Scientist & Business Analyst & Leetcode 面试题 352

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DS Interview Question

How do we choose the factor K?

BA Interview Question

R Programming question: two vectors X and Y are defined as follows X

What will be output of vector Z that is defined as

Z

LeetCode Question

3 Sum Closest

Description: Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

Input: [2, 7, 11, 15]

Output: [0, 1]

Assumptions:  each input would have exactly one solution.

DS Interview Question & Answer

How does the KNN algorithm work?

Answer:

KNN is a supervised machine learning algorithm, basically it works based on minimum distance from the query instance to the training samples to determine the K-nearest neighbors to be the prediction of the query instance. It can be used on both classification and regression problem.

BA Interview Question & Answer

What are the differences among ROWNUM, RANK in SQL?

Answer:

ROW_NUMBER assigns contiguous, unique number from 1.. N ti a result set.

RANK does not assign unique numbers - nor does it assign contiguous numbers. If two records tie for second place, no record will be assigned the 3rd rank as no one came in their, according to RANK.

Examples:

SELECT name, sal, rank() over (order by sal desc) rank_by_sal