Editorial for DMOPC '14 Contest 2 P4 - Deforestation
Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
Submitting an official solution before solving the problem yourself is a bannable offence.
Submitting an official solution before solving the problem yourself is a bannable offence.
We will use a prefix sum array here. Let be the sum of all masses from element
to element
. The sum of all masses from
to
can be expressed as
. The preprocessing time is linear and each query takes constant time. Python users having a hard time should try the PyPy interpreter. Fast input and output methods should be used if possible.
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