62 lines
2.3 KiB
Python
62 lines
2.3 KiB
Python
|
# 设有三条鳄鱼ABC分别站在等边三角形的三个角上，一个人站在三角形的正中间。
|
|||
|
|
# 每条鳄鱼和人的距离为100米，人的奔跑速度是10m/s鳄鱼A的奔跑速度是15m/s鳄鱼B和C的奔跑速度是20m/s。
|
|||
|
|
# 问:这个人最多还能活几秒?
|
|||
|
|
|
|||
|
|
|
|||
|
|
# 贪心算法
|
|||
|
|
#
|
|||
|
|
# 贪心算法（又称贪婪算法）是指，在对问题求解时，总是做出在当前看来是最好的选择。也就是说，不从整体最优上加以考虑，他所做出的是在某种意义上的局部最优解。
|
|||
|
|
#
|
|||
|
|
# 我的做法是：每过一段时间（比如0.1秒）做一次判断，选择此刻延直线距离运动到人 所需时间最短的那只鳄鱼，使人下一时间段所奔跑的方向为背离此鳄鱼的方向。
|
|||
|
|
# 程序中以人为原点建立平面直角坐标系，输出每个时间点人和鳄鱼的坐标。当任意一只鳄鱼在下一时间段内，追上人所需时间小于单位时间，程序结束，并输出人奔跑的总时间。
|
|||
|
|
# 将人和鳄鱼的所有时刻的坐标写入文件，用来画出运动轨迹。
|
|||
|
|
|
|||
|
|
import turtle
|
|||
|
|
|
|||
|
|
positionHuman = (0.00, 86.00)
|
|||
|
|
positionLion1 = (-150.00, 0.00)
|
|||
|
|
positionLion2 = (150.00, 0.00)
|
|||
|
|
positionLion3 = (0.00, 260.00)
|
|||
|
|
escapeDregree = 240
|
|||
|
|
|
|||
|
|
turtle.pensize(3)
|
|||
|
|
for x in range(100):
|
|||
|
|
turtle.color("black")
|
|||
|
|
turtle.penup()
|
|||
|
|
turtle.goto(positionHuman)
|
|||
|
|
turtle.dot(2, "yellow")
|
|||
|
|
turtle.pendown()
|
|||
|
|
turtle.setheading(escapeDregree)
|
|||
|
|
turtle.fd(10)
|
|||
|
|
|
|||
|
|
positionHuman = turtle.position()
|
|||
|
|
|
|||
|
|
turtle.color("green")
|
|||
|
|
turtle.penup()
|
|||
|
|
turtle.goto(positionLion1)
|
|||
|
|
turtle.dot(2, "green")
|
|||
|
|
turtle.pendown()
|
|||
|
|
positionLion1ToHuman = turtle.towards(positionHuman)
|
|||
|
|
turtle.setheading(positionLion1ToHuman)
|
|||
|
|
turtle.forward(15)
|
|||
|
|
positionLion1 = turtle.position()
|
|||
|
|
|
|||
|
|
turtle.color("red")
|
|||
|
|
turtle.penup()
|
|||
|
|
turtle.goto(positionLion2)
|
|||
|
|
turtle.dot(2, "red")
|
|||
|
|
turtle.pendown()
|
|||
|
|
positionLion2ToHuman = turtle.towards(positionHuman)
|
|||
|
|
turtle.setheading(positionLion2ToHuman)
|
|||
|
|
turtle.forward(20)
|
|||
|
|
positionLion2 = turtle.position()
|
|||
|
|
|
|||
|
|
turtle.color("yellow")
|
|||
|
|
turtle.penup()
|
|||
|
|
turtle.goto(positionLion3)
|
|||
|
|
turtle.dot(2, "yellow")
|
|||
|
|
turtle.pendown()
|
|||
|
|
positionLion3ToHuman = turtle.towards(positionHuman)
|
|||
|
|
turtle.setheading(positionLion3ToHuman)
|
|||
|
|
turtle.forward(20)
|
|||
|
|
positionLion3 = turtle.position()
|