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Number of Pairs of Interchangeable Rectangles

MediumArrays

Two rectangles are interchangeable if their width-to-height ratios are equal. Count the number of interchangeable pairs.

Input format (stdin): the first line has n. Each of the next n lines has two integers width and height. Output the number of interchangeable pairs.

Examples
Input: 6 4 8 3 6 10 20 15 30 2 1 4 2
Output: 7
Four rectangles share ratio 1/2 (6 pairs) and two share ratio 2 (1 pair), totalling 7.
Constraints
  • 1 <= n <= 10^5
  • 1 <= width, height <= 10^5
Sheets
NeetCode 250
number-of-pairs-of-interchangeable-rectangles.cpp2 sample tests
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Custom input (stdin)
Output

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