TENPACKETS - Editorial

PROBLEM LINK:

Practice
Contest: Division 1
Contest: Division 2
Contest: Division 3
Contest: Division 4

Author: abhi_inav
Tester: tabr
Editorialist: iceknight1093

DIFFICULTY:

669

PREREQUISITES:

None

PROBLEM:

A sells items in:

  • A packet of 2 for X rupees
  • A packed of 4 for Y rupees

Chef wants to buy 10 of the item, what’s the minimum cost to do so?
It is known that X \lt Y \leq 2X.

EXPLANATION:

Since Y\leq 2X, it’s never worse to buy one packet of 4 rather than 2 packets of 2.

So, the optimal way to buy 10 items is to buy 4+4+2, i.e, 2 packets of 4 each, and one packet of 2 items.
The cost of doing this is 2Y + X.

TIME COMPLEXITY

\mathcal{O}(1) per test case.

CODE:

Editorialist's code (Python)
for _ in range(int(input())):
    x, y = map(int, input().split())
    print(2*y + x)