Day 6

Started working out a formula to math this, but gave up and let the computer do it.

d06/input.txt

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+Time:        54     81     70     88
+Distance:   446   1292   1035   1007

d06/main.py

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+from pathlib import Path
+
+
+class Boat:
+    def __init__(self, starting_speed: int, acceleration: int):
+        self.start_speed = starting_speed
+        self.acc = acceleration
+
+    def hold(self, hold_time: int, time_limit: int) -> int:
+        return (time_limit - hold_time) * ((self.acc * hold_time) + self.start_speed)
+
+
+def part1(input: Path) -> int:
+    # Boat properties
+    start_speed = 0
+    acc = 1
+
+    boat = Boat(start_speed, acc)
+
+    with input.open() as f:
+        times = [int(v) for v in next(f).split()[1:]]
+        dists = [int(v) for v in next(f).split()[1:]]
+
+    answer = 1
+    for time_limit, target_distance in zip(times, dists):
+        times = [
+            hold_time
+            for hold_time in range(0, time_limit)
+            if boat.hold(hold_time, time_limit) > target_distance
+        ]
+        answer *= len(times)
+
+    return answer
+
+
+def solve_calculus():
+    # Gave up on this. Been too long since I studied linear algebra
+
+    # Boat properties
+    start_speed = 0
+    acc = 1
+
+    # Round properties
+    time_limit = 7
+    target_distance = 9
+
+    # Variable
+    hold_time = 1
+
+    # Formula
+    # Curve
+    d = (time_limit - hold_time) * ((acc * hold_time) + start_speed)
+    # Line
+    d = target_distance
+
+    target_distance = (time_limit - hold_time) * ((acc * hold_time) + start_speed)
+
+    return d
+
+
+def part2(input: Path) -> int:
+    # Boat properties
+    start_speed = 0
+    acc = 1
+
+    boat = Boat(start_speed, acc)
+
+    with input.open() as f:
+        time_limit = int("".join([v for v in next(f).split()[1:]]))
+        target_distance = int("".join([v for v in next(f).split()[1:]]))
+
+    times = [
+        hold_time
+        for hold_time in range(0, time_limit)
+        if boat.hold(hold_time, time_limit) > target_distance
+    ]
+
+    return len(times)
+
+
+if __name__ == "__main__":
+    # input = Path("sample.txt")
+    input = Path("input.txt")
+    result1 = part1(input)
+    print(f"part1 {result1}")
+
+    result2 = part2(input)
+    print(f"part2 {result2}")

d06/sample.txt

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+Time:      7  15   30
+Distance:  9  40  200