I have tried to make video solution for The Biggest Restaurant (BIGRES): November Cook-Off 2019 Div. 1+2, hoping to help people understand the problem and what was my approach for the same. BIGRES: November Cook-Off 2019: Video Solution
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I think you used vector of integers.
Product of two integers will result in an integer.
So try vector of long long instead.
However I didn’t test it, try and let me know