Solution to problem 6 in Python

src/Year_2023/Day06.py

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+# --- Day 6: Wait For It ---
+
+# The ferry quickly brings you across Island Island. After asking around, you
+# discover that there is indeed normally a large pile of sand somewhere near
+# here, but you don't see anything besides lots of water and the small island
+# where the ferry has docked.
+
+# As you try to figure out what to do next, you notice a poster on a wall near
+# the ferry dock. "Boat races! Open to the public! Grand prize is an
+# all-expenses-paid trip to Desert Island!" That must be where the sand comes
+# from! Best of all, the boat races are starting in just a few minutes.
+
+# You manage to sign up as a competitor in the boat races just in time. The
+# organizer explains that it's not really a traditional race - instead, you will
+# get a fixed amount of time during which your boat has to travel as far as it
+# can, and you win if your boat goes the farthest.
+
+# As part of signing up, you get a sheet of paper (your puzzle input) that lists
+# the time allowed for each race and also the best distance ever recorded in
+# that race. To guarantee you win the grand prize, you need to make sure you go
+# farther in each race than the current record holder.
+
+# The organizer brings you over to the area where the boat races are held. The
+# boats are much smaller than you expected - they're actually toy boats, each
+# with a big button on top. Holding down the button charges the boat, and
+# releasing the button allows the boat to move. Boats move faster if their
+# button was held longer, but time spent holding the button counts against the
+# total race time. You can only hold the button at the start of the race, and
+# boats don't move until the button is released.
+
+# For example:
+
+# Time:      7  15   30
+# Distance:  9  40  200
+
+# This document describes three races:
+
+#     The first race lasts 7 milliseconds. The record distance in this race is
+# 9 millimeters.
+#     The second race lasts 15 milliseconds. The record distance in this race is
+# 40 millimeters.
+#     The third race lasts 30 milliseconds. The record distance in this race is
+# 200 millimeters.
+
+# Your toy boat has a starting speed of zero millimeters per millisecond. For
+# each whole millisecond you spend at the beginning of the race holding down the
+# button, the boat's speed increases by one millimeter per millisecond.
+
+# So, because the first race lasts 7 milliseconds, you only have a few options:
+
+#     Don't hold the button at all (that is, hold it for 0 milliseconds) at the
+# start of the race. The boat won't move; it will have traveled 0 millimeters by
+# the end of the race.
+#     Hold the button for 1 millisecond at the start of the race. Then, the boat
+# will travel at a speed of 1 millimeter per millisecond for 6 milliseconds,
+# reaching a total distance traveled of 6 millimeters.
+#     Hold the button for 2 milliseconds, giving the boat a speed of 2
+# millimeters per millisecond. It will then get 5 milliseconds to move, reaching
+# a total distance of 10 millimeters.
+#     Hold the button for 3 milliseconds. After its remaining 4 milliseconds of
+# travel time, the boat will have gone 12 millimeters.
+#     Hold the button for 4 milliseconds. After its remaining 3 milliseconds of
+# travel time, the boat will have gone 12 millimeters.
+#     Hold the button for 5 milliseconds, causing the boat to travel a total of
+# 10 millimeters.
+#     Hold the button for 6 milliseconds, causing the boat to travel a total of
+# 6 millimeters.
+#     Hold the button for 7 milliseconds. That's the entire duration of the
+# race. You never let go of the button. The boat can't move until you let go of
+# the button. Please make sure you let go of the button so the boat gets to
+# move. 0 millimeters.
+
+# Since the current record for this race is 9 millimeters, there are actually 4
+# different ways you could win: you could hold the button for 2, 3, 4, or 5
+# milliseconds at the start of the race.
+
+# In the second race, you could hold the button for at least 4 milliseconds and
+# at most 11 milliseconds and beat the record, a total of 8 different ways to
+# win.
+
+# In the third race, you could hold the button for at least 11 milliseconds and
+# no more than 19 milliseconds and still beat the record, a total of 9 ways you
+# could win.
+
+# To see how much margin of error you have, determine the number of ways you can
+# beat the record in each race; in this example, if you multiply these values
+# together, you get 288 (4 * 8 * 9).
+
+# Determine the number of ways you could beat the record in each race. What do
+# you get if you multiply these numbers together?
+
+with open("files/P6.txt") as f:
+    times, distances = [line for line in f.read().strip().split("\n")]
+
+times = [int(t) for t in times.split(":")[1].split()]
+distances = [int(d) for d in distances.split(":")[1].split()]
+
+
+def part1():
+    total = 1
+    for idx, time in enumerate(times):
+        res = 0
+        for t in range(time):
+            d = t * (time - t)
+            if d > distances[idx]:
+                res += 1
+        total *= res
+
+    print(f"There are {total} ways of beating the record")
+
+
+# --- Part Two ---
+
+# As the race is about to start, you realize the piece of paper with race times
+# and record distances you got earlier actually just has very bad kerning.
+# There's really only one race - ignore the spaces between the numbers on each
+# line.
+
+# So, the example from before:
+
+# Time:      7  15   30
+# Distance:  9  40  200
+
+# ...now instead means this:
+
+# Time:      71530
+# Distance:  940200
+
+# Now, you have to figure out how many ways there are to win this single race.
+# In this example, the race lasts for 71530 milliseconds and the record distance
+# you need to beat is 940200 millimeters. You could hold the button anywhere
+# from 14 to 71516 milliseconds and beat the record, a total of 71503 ways!
+
+# How many ways can you beat the record in this one much longer race?
+
+time = int("".join(str(t) for t in times))
+distance = int("".join(str(d) for d in distances))
+
+
+def part2():
+    total = 0
+    for t in range(time):
+        d = t * (time - t)
+        if d > distance:
+            total += 1
+
+    print(f"There are {total} ways of beating the record")
+
+
+if __name__ == "__main__":
+    part1()
+    part2()