用pygame编写多个球各自移动，两球相撞互相反弹，球碰到边界反弹，球通过点击屏幕产生。

import pygame
import random
pygame.init()
window = pygame.display.set_mode((400, 600))
window.fill((255, 255, 255))
pygame.display.flip()
circle_list = []
ball_list = [] #接触的球列表
while True:
    pygame.time.delay(10)
    window.fill((255, 255, 255))
    for item in circle_list:
        pygame.draw.circle(window, item['color:'], (item['circle_x:'], item['circle_y:']), 20, 0)
        item['circle_x:'] += item['x_speed:']
        item['circle_y:'] += item['y_speed:']
        if 20<item['circle_x:']<380 and 20<item['circle_y:']<580:
            for other in circle_list:
                if ((item['circle_x:']-other['circle_x:'])**2+(item['circle_y:']-other['circle_y:'])**2)**0.5<=40 and item !=other :
                    item['x_speed:'] *= -1
                    item['y_speed:'] *= -1
                    break
        if item['circle_x:']< 20 :
            item['circle_x:'] = 20
            item['x_speed:'] *= -1
        if item['circle_x:']> 380 :
            item['circle_x:'] = 380
            item['x_speed:'] *= -1
        if item['circle_y:']< 20 :
            item['circle_y:'] = 20
            item['y_speed:'] *= -1
        if item['circle_y:']> 580 :
            item['circle_y:'] = 580
            item['y_speed:'] *= -1

    pygame.display.flip()
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            exit()
        elif event.type == pygame.MOUSEBUTTONDOWN:
            color = (random.randint(0,255),random.randint(0,255),random.randint(0,255))
            x, y = event.pos
            count = 0
            for item in circle_list:
                if  ((item['circle_x:']-x)**2+(item['circle_y:']-y)**2)**0.5<=40:
                    count = 1
            if count == 1:
                continue
            list1 = [-2,-1,1,2]
            x_speed = list1[random.randint(0,3)]
            y_speed = list1[random.randint(0,3)]
            if  20<=x<380 and 20<y<580:
                circle_dict = {'color:':color,'circle_x:': x, 'circle_y:': y,'x_speed:':x_speed,'y_speed:':y_speed}
                circle_list.append(circle_dict)