Write a program that lets the user play the game of Rock, Paper, Scissors against the computer. The program should work as follows: When the program begins, a random number in the range of 1 through 3 is generated. If the number is 1, then the computer has chosen rock. If the number is 2, then the computer has chosen paper. If the number is 3, then the computer has chosen scissors. (Do not display the computer's choice yet) The user enters his or her choice of "rock", "paper, or "scissors" at the keyboard. The computer's choice is displayed. A winner is selected according to the following rules: If one player chooses rock and the other player chooses scissors, then rock wins. (Rock smashes scissors.) If one player chooses scissors and the other player chooses paper, then scissors wins. (Scissors cuts paper.) If one player chooses paper and the other play chooses rock, then paper wins (Paper wraps rock.) If both players make the same choice, the game must be played again to determine the winner.

Here is the Python program for the game rock, paper, scissors.

import random

def computerChoice():  #function for the computers choice

   randomNumber = random.randint(1,3)  

# generates random no in the range of 1 through 3

   if randomNumber == 1:  #if that random number is equal to 1

       return 'rock'  #computer has chosen rock

   elif randomNumber == 2:  #if random number is equal to 2

       return 'paper' #computer has chosen paper

   else:

       return 'scissors'  #computer has chosen scissors

def validChoice(choice):  #function which checks if user enters right choice

   return choice == 'rock' or choice == 'paper' or choice == 'scissors'

    #the right choice is one of the following rock paper or scissor

def invalidChoice(choice):  #function to check if user entered invalid choice

#loop continues until the user enter the correct given choice

   while choice != 'rock' and choice != 'paper' and choice != 'scissors':

         print('That is not a valid choice.')  

         choice = input('\nEnter rock, paper, or scissors: ')

   return choice

def winner(player, computer): # function to decide who wins the game

   if player == 'rock' and computer == 'scissors':  

#if player chooses rock and computer has chosen scissors

       print("rock smashes scissors")  #display this message

       return True  #function returns true

        #if player chooses scissors and computer has chosen paper

   elif player == 'scissors' and computer == 'paper':

       print("scissors cuts paper")

       return True

     #if player chooses paper and computer has chosen rock

   elif player == 'paper' and computer == 'rock':

       print("paper wraps rock")

       return True          

   else:

       return False  

compChoice = computerChoice()  #stores the choice made by computer

playerChoice = input('Choose from rock, paper, or scissors: ')

#stores what player inputs as his choice

if not validChoice(playerChoice):  #if the choice is not valid

   playerChoice = invalidChoice(playerChoice)  

#calls invalid function to take valid input choice from user

while playerChoice == compChoice:  

#loop continues to execute until the winner is decided

   print('Computer\'s choice:', compChoice)

#if there is a tie then the game is played again to determine the winner

   print('Its a tie!  Choose again.')      

   compChoice = computerChoice()

   playerChoice = input('\nEnter rock, paper, or scissors: ')

   if not validChoice(playerChoice):

       playerChoice = invalidChoice(playerChoice)

#if player wins congratulation message is displayed

print('Computer\'s choice:', compChoice)

if winner(playerChoice, compChoice):

   print('Congratulations! You win!')

else:  #if player loses from computer

   print('You lose! Computer wins!')  

Explanation:

This program has following methods:

computerChoice() This function generates random number in the range of 1 through 3 to take choice from the computer and it uses random.randint() to generate random number from the given range. If the random number is 1 then the computer has chosen rock and if random number is 2 then the computer has chosen paper otherwise scissors.

validChoice() function sets the choice variable to rock, paper and scissors which means user should enter one of these available choices.

invalidChoice() function checks if user entered invalid choice. Invalid choice is anything entered other than rock, paper, scissors. While loop continues to execute and keeps asking to enter a choice until the user enter the correct given choice. It displays That is not a valid choice if user enters an invalid choice.

winner() function determines the winner between computer and player by comparing the choices entered by player and computer. For example if the player enters rock and computer has chosen scissors then this message is displayed rock smashes scissors and function returns true. This means player wins.

Lastly the main program prompts user to enter a choice and stores computer's choice too and compares both the choices to determine the winner accordingly. If there is tie then the game is started again to determine the winner.

The output is attached.