Histogram doubt

in histogram problem at leet code


by this code im getting error that
line:924 : char 9: runtime error: reference binding to NULL pointer of type ‘int’ (STL_vector.h)
what does this error means and why its coming?

@deepakjumani09 you have shared just the function not complete code.
I will suggest you to use long long int.

Also mark this doubt as resolved.

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