PROBLEM LINK:
Author: avi224
Editorialist: avi224
DIFFICULTY:
CAKEWALK.
PREREQUISITES:
STL
PROBLEM:
Print the sum of all numbers in an array occurring exactly K times. If there is no such number, print -1.
EXPLANATION:
This can be implemented by using a map or unordered map in C++. Just take the sum of numbers whose frequency is K, considering each number only once.