AMENITY ENCODER
Beginner
Difficulty: Easy Tags: Data Processing, Classic ML
Story
Every Airbnb listing carries a categorical amenities tag, and the pricing model cannot consume raw strings. This is the encoding step that runs before every single downstream feature touches the model.
The Math
One-hot encode a categorical column of n values into an n x k binary matrix, where k is the
number of distinct categories present, columns ordered alphabetically.
Input Format
n
cat_1
cat_2
...
cat_n
Output Format
First line: the k distinct categories, alphabetically, space-separated. Next n lines: the
one-hot row for each input, space-separated 0/1.
Constraints
1 <= n <= 10^4, category strings up to 20 characters- Time limit: 1.0 second.
Example
Input
5
wifi
parking
wifi
pool
parking
Output
parking pool wifi
0 0 1
1 0 0
0 0 1
0 1 0
1 0 0
Keywords
data-processingclassical-ml
Python
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