6. Exercise: Paper, Scissors, Stone game

Let's use what we have learn so far to build a simple game: Paper, Scissors, Stone.

First, we want to map out the logic of the game, which will help us build a series of if...elsif... statements. There can only be finite number of results, as shown below:

Human (you)	Computer	Result
Paper	Scissors	You lose
Paper	Stone	You win
Paper	Paper	Draw
Scissors	Paper	You win
Scissors	Stone	You lose
Scissors	Scissors	Draw
Stone	Scissors	You win
Stone	Paper	You lose
Stone	Stone	Draw

Now, we are ready to capture the above logic into a series of if...elsif... statements:

if human== "paper" and computer  == "scissors":
  print("You lose")
elif human== "paper" and computer == "stone":
  print("You win")
elif human== "paper" and computer == "paper":
  print("Draw")
elif human== "scissors" and computer == "paper":
  print("You win")
elif human== "scissors" and computer == "stone":
  print("You lose")
elif human== "scissors" and computer == "scissors":
  print("Draw")
elif human== "stone" and computer == "scissors":
  print("You win")
elif human== "stone" and computer == "paper":
  print("You lose")
elif human== "stone" and computer == "stone":
  print("Draw")

You can also add a user input using input() function, randomized the computer choice using random.randin() function, as well as adding an else "end all" condition to improve the game:

import random

human = input("Your choice? ")

comp = random.randint(1,3)
if comp==1:
  computer = "paper"
elif comp==2:
  computer = "scissors"
elif comp==3:
  computer = "stone"
print("Computer choice: " + computer)

if human== "paper" and computer  == "scissors":
  print("You lose")
elif human== "paper" and computer == "stone":
  print("You win")
elif human== "paper" and computer == "paper":
  print("Draw")
elif human== "scissors" and computer == "paper":
  print("You win")
elif human== "scissors" and computer == "stone":
  print("You lose")
elif human== "scissors" and computer == "scissors":
  print("Draw")
elif human== "stone" and computer == "scissors":
  print("You win")
elif human== "stone" and computer == "paper":
  print("You lose")
elif human== "stone" and computer == "stone":
  print("Draw")
else:
  print("Invalid input.")