Inlägg "I have a question about the problem formulation ..." | Problemlösning och programmering under press (DD2458)

I have a question about the problem formulation in problem Ljutnja (https://kth.kattis.com/problems/ljutnja)

There is a note in the output section of the problem "Note: The test cases will ensure that the result fits in a 64-bit unsigned integer.".

Does this mean that the we should give the answer in a 64-bit unsigned integer, or that answers will never overflow if we use 64-bit unsigned integers?

It means that you can assume that the input satisfies the property that the correct answer, which is an integer, lies between 0 and 18446744073709551615 (inclusive).

(I'm not really sure what you mean by "give the answer in a 64-bit unsigned integer": you always give the answer as a string of digits.)

I might be wrong, let's double check. Compare my submissions id 756596 and 765908:

In both i print the answer using python 3.4 integers which have "unlimited" precision. In one i take the answer mod 2^64. I get correct answer in the one using modulus. I suspect this means that there is a test where the correct answer is larger than 2^64. Such a testcase is possible, e.g. all children want 2*10^9, there are 10^5 children, and only 1 candy, yielding about 22000 times more anger than can fit in a 64 bit unsigned integer. Correct?

Good catch, thanks! The test data for the problem indeed contained some invalid test cases where the correct answer exceeded 64 bits.

I have fixed this, and all old non-Accepted submissions are currently being rejudged -- your initial submissions using unlimited precision will switch state to Accepted in a little while.