Pascal Lais
a81a510d6b
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56 lines
2.1 KiB
Python
56 lines
2.1 KiB
Python
#!/usr/bin/env python3
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from pathlib import Path
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def part_1(input):
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"""The max height is reached by using the maximum start y velocity that doesn't overshoot the
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landing area. The x velocity doesn't mater here, because x position won't change after x
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velocity reaches 0. So there will always be an vx that drops straight between the x boundaries.
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Because the y velocity decreases linear we will reach our starting height after the velocity
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changed exactly to the negative value of our starting velocity. At this point we have to make
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sure not to overhoot the landing area, so the next velocity needs to be the same value as the
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lowest coordinate of the landing area to be able to start with the highest possible starting
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velocity. This leaves us with a starting velocity of abs(y_min + 1) to reach the maximum
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possible height. For positive landing coordinates y_max has to be used.
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"""
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result = 0
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_, y = input[0].rstrip().replace('target area: ', '').replace(
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'x=', '').replace('y=', '').split(', ')
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y_min, _ = [int(c) for c in y.split('..')]
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vy0 = abs(y_min + 1)
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result = vy0 * (vy0 + 1) // 2
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print("Part 1 result:", result)
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def part_2(input):
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result = 0
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x, y = input[0].rstrip().replace('target area: ', '').replace(
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'x=', '').replace('y=', '').split(', ')
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x_min, x_max = [int(c) for c in x.split('..')]
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y_min, y_max = [int(c) for c in y.split('..')]
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for vx_0 in range(x_max):
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for vy_0 in range(y_min, -y_min):
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vx = vx_0
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vy = vy_0
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x_pos = 0
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y_pos = 0
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while x_pos < x_max and y_pos > y_min:
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x_pos += vx
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y_pos += vy
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if vx != 0:
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vx -= 1
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vy -= 1
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if x_min <= x_pos <= x_max and \
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y_min <= y_pos <= y_max:
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result += 1
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break
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print("Part 2 result:", result)
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input = list()
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p = Path(__file__).with_name('input.txt')
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with open(p) as f:
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input = f.readlines()
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part_1(input)
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part_2(input)
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