https://programmers.co.kr/learn/courses/30/lessons/82612
def solution(price, money, count):
answer = -1
for i in range(1,count+1):
money-=price*i
if money<0:
answer=-money
else:
answer=0
return answer
처음에 price*i
를 해야하는데 price*count
를 해버려서 결과 제대로 안나옴
def solution(price, money, count):
return max(0,price*(count+1)*count//2-money)