ABC 138 screencast

https://atcoder.jp/contests/abc138/tasks

https://drive.google.com/file/d/15FST30n57Kb4yDPkUfNV4E4XR8qL8XLN/view

Problem C We should use items in ascending order because the first item thrown into the bin is finally multiplied by 1/2**(N-1).
Problem D I think the problem C is more difficult than the problem D.
Problem E We can find subsequence greedily. We just speed up it.
Problem F In binary representation, the number of digits of x and y must be the same. If same, y % x is equivalent to y-x. y-x and x^y is the same if and only if y-x has no borrows. Similar fact appears in recent ABC, which is not subtraction but addition. Therefore, we can solve it using digit DP.