arunkumar8202's blog

Bug in Codeforces C++ Compiler
By arunkumar8202, history, 19 months ago, In English

Hello community,

I was trying to solve the question 699C Fence Painting during which I came across a interesting bug in C++ compiler which I couldn't figure out.

I tried to submit to same solution using three different versions of C++ and it gave different result on each run.

C++ 14 : The solution got accepted 173550755

C++ 17 : The solution gave wrong answer on testcase 3 173550802

C++ 20 : The solution got runtime error on testcase 3 173550866

MikeMirzayanov will you please look into the matter or clarify if I have made a mistake. Any kind of help will be appreciated.

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19 months ago, # |
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19 months ago, # |
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Your code uses undefined behaviour s.lower_bound({v2[i],0}) could be the end iterator which you are not allowed to dereference.

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