Problem 661. Spot the outlier

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All points except for one lie on a line. Which one is the outlier?

Example:

You are given a list of x-y pairs in a column like this:

 pts = [ 0 1 
         0 2 
         3 2
         0 3 
         0 4 ]

You would return the number 3, since the third point is the only one that is non-collinear with the other points. All the others are on the y-axis.

 outlier = 3

Solve

Solution Stats

Last solution submitted on Jul 11, 2019

Last 200 Solutions

Problem Comments

2 Comments

2 Comments

Justin on 29 Apr 2014

The instructions were a bit confusing at first. It would have been better to say "Find the row number of the outlying point."

Also, using the third row as an answer and a 3 in a column of zeros makes it seem like the intent was to provide unclear instructions. (Or they are just used to writing college textbooks ;) )

Wenwu on 8 Jan 2015

The test set cases 2,3 seems to have two outliers for each case. Please check it

Solution Comments

Solution 1015114

2 Comments

2 Comments

Hoai Tran Quoc on 13 Oct 2016

Very interesting, why the test# 3 is not passed. It turned out that the two number
(x4-x1)*(y2-y1) is not the same as (y4-y1)*(x2-x1) due to floating point. I have to compare the subtraction with 10*eps.

Hoai Tran Quoc on 14 Oct 2016

Very interesting. I could not understand why I had not passed the test# 3. It turned out that the two number (x4-x1)*(y2-y1) and (y4-y1)*(x2-x1) are not the same due to floating point. My choice is to compare the absolute difference with 10*eps.

Solution 897667