Can someone please tell me why does this happen?
Submission(AC)
Submission(WA)
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Can someone please tell me why does this happen?
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First of all the code in the two submissions is not the same. However, fixing this difference does not explain the discrepancy.
The issue lies in the line
else m[c] = --c, --k;
which does a bunch of weird things including setting m[c] while modifying c in the middle of the expression, as well as using the comma operator.In fact, after C++17, it wll first evaluate rhs then lhs so
m[c] = --c
is not UB...