from random import randint
import turtle
import math


number_of_turtles = 20
steps_of_time_number = 300
turtle.screensize(100, 150)


pool = [turtle.Turtle(shape='turtle') for i in range(number_of_turtles)]
for unit in pool:
    unit.penup()
    unit.speed(350)
    unit.goto(randint(-200, 200), randint(-150, 150))
    unit.left(randint(-180, 180))
    unit.rev_x = False
    unit.rev_y = False


for i in range(steps_of_time_number):
    for unit in pool:
        x, y = unit.xcor(), unit.ycor()
        if abs(x) >= turtle.screensize()[0] and not unit.rev_x:
            unit.seth(90 - unit.heading())
            unit.rev_x = True
        elif not abs(x) >= turtle.screensize()[0]:
            unit.rev_x = False
        if abs(y) >= turtle.screensize()[1] and not unit.rev_y:
            unit.seth(-unit.heading())
            unit.rev_y = True
        elif abs(y) < turtle.screensize()[1]:
            unit.rev_y = False
        unit.forward(7)
        for another_unit in pool:
            if another_unit == unit:
                continue
            if math.hypot(another_unit.xcor() - unit.xcor(), another_unit.ycor() - unit.ycor()) < 6:
                angle = randint(-180, 180)
                unit.seth(angle)
                another_unit.seth(-angle)
                unit.forward(2)
                another_unit.forward(2)