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Subject: OT: CSES Number Spiral algorithm
Date: Thu, 20 Mar 2025 12:47:11 -0400
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I don't have a C question, but rather I'd like input about algorithmic 
approaches.

https://cses.fi/problemset/task/1071

It's an 'infinite grid'.  You have to find the value at rows-columns 
from 1 to 10^9.

First thing you notice about the 5x5 grid is the values in odd-numbered 
columns begin with the square of the column number, and the values in 
even-numbered rows begin with the square of the row number.

I followed the number pattern and built a grid in Excel and expanded it 
to 10x10 for more testing.

https://imgur.com/x4VymmA

Then coded 4 conditions      solution
1. row <= col and col odd    (col * col) - row + 1
2. row <= col and col even   ((col-1) * (col-1)) + row
3. row >  col and row odd    ((row-1) * (row-1)) + col
4. row >  col and row even   (row * row) - col + 1

My full C code submission was accepted the first time.

How would you have done it?