description
you are given an array and you are asked to make (k) elements of it equal after some operations.
you can make one of the following operations:
- take one of the minimum and increase its value by (1)
- take one of the maximum and subtract (1) from it
find the minimum number of operations to make it possible.
breakthough
this problem involves nothing but implimention. but we can make it elegantly.
let conclusion comes first, our required answer is
(ans=min((ansl,ansr),ansmid)) ，where:
- (ansl) is the needed operations if we choose to share value (a[k]) with no less than (k) elements.
- (ansr) is the needed operations if we choose to share value (a[n-k+1]) with no less than (k) elements.
- (ansmid) is the needed operations if we choose to let (k) elements staying right in the middle be the chosen ones(who is exactly among the k numbers chosen)
most of the times our answer is contributed by (ansl) or (ansr) except some cases like test case number two given by the host, in which both the minimum and maximum are extremely close as well as the chosen one is in between.
apart from things above there are also some tricks here related to the constraints of the application of each answer, which is amazing to generate or come out。。。
code to take a reference:https://codeforces.com/contest/1328/submission/74425585