Czech ACM Student Chapter
Czech Technical University in Prague
Charles University in Prague
Technical University of Ostrava
acm
ˇ a
Slovak University of Technology
Pavol Jozef Saf´rik University in Koˇice
s
cz
ˇ
University of Zilina
Masaryk University
Matej Bel University in Bansk´ Bystrica
a
University of West Bohemia
CTU Open Contest 2013
Fractional Lotion
fl.c, fl.cpp, Fl.java
Freddy practices various kinds of alternative medicine, such as homeopathy. This practice is
based on the belief that successively diluting some substances in water or alcohol while shaking
them thoroughly produces remedies for many diseases.
This year, Freddy's vegetables appear to have caught some disease and he decided to experiment
a little bit and investigate whether homeopathy works for vegetables too. As Freddy is also a big
fan of mathematics, he does not strictly insist that the substances have small concentrations,
but he instead requires the concentrations to be reciprocals of integers (1/n). In experiments,
some of the vegetables really got much better.
Seeing Freddy's successes, a fellow gardener also wants to try one of these potions and asks for
a flask. Freddy has one flask of the potion in concentration 1/n and does not want to give it
all out. Your task is to find out in how many ways the potion can be split into two flasks and
diluted so that the resulting potions both have the same volume as the original one and the
resulting concentrations also are reciprocals of integers -- we do not want to end up with useless
fluid, do we?
Input Specification
Each line of the input describes one test case. The line contains the expression "1/n" representing
the original concentration. You are guaranteed that 1 n 10 000. There are no spaces on the
line.
Output Specification
For each test case, output a single line with the total number of distinct pairs {x, y} of positive
integers satisfying 1/x + 1/y = 1/n. Pairs differing only in the order of the two numbers are not
considered different.
Output for Sample Input
Sample Input
2
1/2
3
1/4
1
1/1
32
1/5000
This problem was inspired by Project Euler