ex_05_4.py

#!/usr/bin/python
#AUTHOR: alexxa
#DATE: 24.12.2013
#SOURCE: Think Python: How to Think Like a Computer Scientist by Allen B. Downey
# http://www.greenteapress.com/thinkpython/html/index.html
#PURPOSE: Chapter 5. Conditionals and recursion

# Exercise 5.4

# If you are given three sticks, you may or may not be able 
# to arrange them in a triangle. For example, if one of the sticks 
# is 12 inches long and the other two are one inch long, it is clear 
# that you will not be able to get the short sticks to meet in the middle.
# For any three lengths, there is a simple test to see if it is possible 
# to form a triangle: 
# If any of the three lengths is greater than the sum of the other two, 
# then you cannot form a triangle. Otherwise, you can. (If the sum of 
# two lengths equals the third, they form what is called a degenerate triangle.)
# 1. Write a function named is_triangle that takes three integers as arguments, 
# and that prints either Yes or No, depending on whether you can or cannot 
# form a triangle from sticks with the given lengths.

def is_triangle(x, y, z):
    if z > (x+y) or y > (x+z) or x > (y+z):
        print('No')
    else:
        print('Yes')

is_triangle(1, 2, 3) # it's possible to arrange a triangle
is_triangle(1, 2, 9) # it's not possible to arrange a triangle
print()

# 2. Write a function that prompts the user to input three stick lengths, 
# converts them to integers, and uses is_triangle to check whether sticks 
# with the given lengths can form a triangle.

def triangle():
    x = int(input('Please enter the length of the 1st stick:\n'))
    y = int(input('Please enter the length of the 2nd stick:\n'))
    z = int(input('Please enter the length of the 3rd stick:\n'))
    is_triangle(x, y, z)
    
triangle()


#END