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```"""
Sample Python/Pygame Programs
Simpson College Computer Science
http://simpson.edu/computer-science/

Explanation video: http://youtu.be/qbEEcQXw8aw
"""

import pygame
import random

# Define some colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)

class Block(pygame.sprite.Sprite):
"""
This class represents the ball
It derives from the "Sprite" class in Pygame
"""
def __init__(self, color, width, height):
""" Constructor. Pass in the color of the block,
and its x and y position. """
# Call the parent class (Sprite) constructor
super().__init__()

# Create an image of the block, and fill it with a color.
# This could also be an image loaded from the disk.
self.image = pygame.Surface([width, height])
self.image.fill(color)

# Fetch the rectangle object that has the dimensions of the image
# image.
# Update the position of this object by setting the values
# of rect.x and rect.y
self.rect = self.image.get_rect()

def reset_pos(self):
""" Reset position to the top of the screen, at a random x location.
Called by update() or the main program loop if there is a collision.
"""
self.rect.y = random.randrange(-300, -20)
self.rect.x = random.randrange(0, screen_width)

def update(self):
""" Called each frame. """

# Move block down one pixel
self.rect.y += 1

# If block is too far down, reset to top of screen.
if self.rect.y > 410:
self.reset_pos()

class Player(Block):
""" The player class derives from Block, but overrides the 'update'
functionality with new a movement function that will move the block
with the mouse. """
def update(self):
# Get the current mouse position. This returns the position
# as a list of two numbers.
pos = pygame.mouse.get_pos()

# Fetch the x and y out of the list,
# just like we'd fetch letters out of a string.
# Set the player object to the mouse location
self.rect.x = pos[0]
self.rect.y = pos[1]

# Initialize Pygame
pygame.init()

# Set the height and width of the screen
screen_width = 700
screen_height = 400
screen = pygame.display.set_mode([screen_width, screen_height])

# This is a list of 'sprites.' Each block in the program is
# added to this list. The list is managed by a class called 'Group.'
block_list = pygame.sprite.Group()

# This is a list of every sprite. All blocks and the player block as well.
all_sprites_list = pygame.sprite.Group()

for i in range(50):
# This represents a block
block = Block(BLACK, 20, 15)

# Set a random location for the block
block.rect.x = random.randrange(screen_width)
block.rect.y = random.randrange(screen_height)

# Add the block to the list of objects

# Create a red player block
player = Player(RED, 20, 15)

# Loop until the user clicks the close button.
done = False

# Used to manage how fast the screen updates
clock = pygame.time.Clock()

score = 0

# -------- Main Program Loop -----------
while not done:
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True

# Clear the screen
screen.fill(WHITE)

# Calls update() method on every sprite in the list
all_sprites_list.update()

# See if the player block has collided with anything.
blocks_hit_list = pygame.sprite.spritecollide(player, block_list, False)

# Check the list of collisions.
for block in blocks_hit_list:
score += 1
print(score)

# Reset block to the top of the screen to fall again.
block.reset_pos()

# Draw all the spites
all_sprites_list.draw(screen)

# Limit to 20 frames per second
clock.tick(20)

# Go ahead and update the screen with what we've drawn.
pygame.display.flip()

pygame.quit()

```
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