67 lines
1.5 KiB
Python
67 lines
1.5 KiB
Python
#!/usr/bin/env python3
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"""Navigation computer of the SS Probably Fine.
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Usage: python3 nav.py DESTINATION
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"""
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import sys
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# Distances between neighboring waypoints, in million km.
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DISTANCES = {
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("earth", "moon"): 0.4,
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("earth", "gateway"): 0.4,
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("gateway", "mars"): 225.0,
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}
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# Every route starts at Earth.
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ROUTES = {
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"moon": ["earth", "moon"],
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"mars": ["earth", "gateway", "mars"],
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}
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NAMES = {
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"earth": "Earth",
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"moon": "Moon",
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"gateway": "Lunar Gateway",
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"mars": "Mars",
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}
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CRUISE_SPEED = 0.87 # million km per day
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FUEL_PER_MKM = 0.142 # tonnes of fuel per million km
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LAUNCH_FUEL = 380.0 # tonnes of fuel to escape Earth's gravity
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def distance(a, b):
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if (a, b) in DISTANCES:
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return DISTANCES[(a, b)]
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return DISTANCES[(b, a)]
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def legs(route):
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return [(route[i], route[i + 1]) for i in range(len(route) - 1)]
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def plan(destination):
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route = ROUTES[destination]
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total = 0.0
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fuel = 0.0
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for start, end in legs(route):
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d = distance(start, end)
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total += d
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fuel += d * FUEL_PER_MKM
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if start == "earth":
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fuel += LAUNCH_FUEL
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return route, total, total / CRUISE_SPEED, fuel
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def main():
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destination = sys.argv[1]
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route, total, days, fuel = plan(destination)
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print("Route: " + " -> ".join(NAMES[w] for w in route))
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print(f"Distance: {total:.1f} million km")
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print(f"Travel time: {round(days)} days")
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print(f"Fuel required: {round(fuel)} t")
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if __name__ == "__main__":
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main()
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