[WIP] Solution to problem 10 part 2! in Python

src/Year_2018/P10.py

@@ -0,0 +1,195 @@
+# --- Day 10: The Stars Align ---
+
+# It's no use; your navigation system simply isn't capable of providing walking
+# directions in the arctic circle, and certainly not in 1018.
+
+# The Elves suggest an alternative. In times like these, North Pole rescue
+# operations will arrange points of light in the sky to guide missing Elves
+# back to base. Unfortunately, the message is easy to miss: the points move
+# slowly enough that it takes hours to align them, but have so much momentum
+# that they only stay aligned for a second. If you blink at the wrong time, it
+# might be hours before another message appears.
+
+# You can see these points of light floating in the distance, and record their
+# position in the sky and their velocity, the relative change in position per
+# second (your puzzle input). The coordinates are all given from your
+# perspective; given enough time, those positions and velocities will move the
+# points into a cohesive message!
+
+# Rather than wait, you decide to fast-forward the process and calculate what
+# the points will eventually spell.
+
+# For example, suppose you note the following points:
+
+# position=< 9,  1> velocity=< 0,  2>
+# position=< 7,  0> velocity=<-1,  0>
+# position=< 3, -2> velocity=<-1,  1>
+# position=< 6, 10> velocity=<-2, -1>
+# position=< 2, -4> velocity=< 2,  2>
+# position=<-6, 10> velocity=< 2, -2>
+# position=< 1,  8> velocity=< 1, -1>
+# position=< 1,  7> velocity=< 1,  0>
+# position=<-3, 11> velocity=< 1, -2>
+# position=< 7,  6> velocity=<-1, -1>
+# position=<-2,  3> velocity=< 1,  0>
+# position=<-4,  3> velocity=< 2,  0>
+# position=<10, -3> velocity=<-1,  1>
+# position=< 5, 11> velocity=< 1, -2>
+# position=< 4,  7> velocity=< 0, -1>
+# position=< 8, -2> velocity=< 0,  1>
+# position=<15,  0> velocity=<-2,  0>
+# position=< 1,  6> velocity=< 1,  0>
+# position=< 8,  9> velocity=< 0, -1>
+# position=< 3,  3> velocity=<-1,  1>
+# position=< 0,  5> velocity=< 0, -1>
+# position=<-2,  2> velocity=< 2,  0>
+# position=< 5, -2> velocity=< 1,  2>
+# position=< 1,  4> velocity=< 2,  1>
+# position=<-2,  7> velocity=< 2, -2>
+# position=< 3,  6> velocity=<-1, -1>
+# position=< 5,  0> velocity=< 1,  0>
+# position=<-6,  0> velocity=< 2,  0>
+# position=< 5,  9> velocity=< 1, -2>
+# position=<14,  7> velocity=<-2,  0>
+# position=<-3,  6> velocity=< 2, -1>
+
+# Each line represents one point. Positions are given as <X, Y> pairs: X
+# represents how far left (negative) or right (positive) the point appears,
+# while Y represents how far up (negative) or down (positive) the point
+# appears.
+
+# At 0 seconds, each point has the position given. Each second, each point's
+# velocity is added to its position. So, a point with velocity <1, -2> is
+# moving to the right, but is moving upward twice as quickly. If this point's
+# initial position were <3, 9>, after 3 seconds, its position would become
+# <6, 3>.
+
+# Over time, the points listed above would move like this:
+
+# Initially:
+# ........#.............
+# ................#.....
+# .........#.#..#.......
+# ......................
+# #..........#.#.......#
+# ...............#......
+# ....#.................
+# ..#.#....#............
+# .......#..............
+# ......#...............
+# ...#...#.#...#........
+# ....#..#..#.........#.
+# .......#..............
+# ...........#..#.......
+# #...........#.........
+# ...#.......#..........
+
+# After 1 second:
+# ......................
+# ......................
+# ..........#....#......
+# ........#.....#.......
+# ..#.........#......#..
+# ......................
+# ......#...............
+# ....##.........#......
+# ......#.#.............
+# .....##.##..#.........
+# ........#.#...........
+# ........#...#.....#...
+# ..#...........#.......
+# ....#.....#.#.........
+# ......................
+# ......................
+
+# After 2 seconds:
+# ......................
+# ......................
+# ......................
+# ..............#.......
+# ....#..#...####..#....
+# ......................
+# ........#....#........
+# ......#.#.............
+# .......#...#..........
+# .......#..#..#.#......
+# ....#....#.#..........
+# .....#...#...##.#.....
+# ........#.............
+# ......................
+# ......................
+# ......................
+
+# After 3 seconds:
+# ......................
+# ......................
+# ......................
+# ......................
+# ......#...#..###......
+# ......#...#...#.......
+# ......#...#...#.......
+# ......#####...#.......
+# ......#...#...#.......
+# ......#...#...#.......
+# ......#...#...#.......
+# ......#...#..###......
+# ......................
+# ......................
+# ......................
+# ......................
+
+# After 4 seconds:
+# ......................
+# ......................
+# ......................
+# ............#.........
+# ........##...#.#......
+# ......#.....#..#......
+# .....#..##.##.#.......
+# .......##.#....#......
+# ...........#....#.....
+# ..............#.......
+# ....#......#...#......
+# .....#.....##.........
+# ...............#......
+# ...............#......
+# ......................
+# ......................
+
+# After 3 seconds, the message appeared briefly: HI. Of course, your message
+# will be much longer and will take many more seconds to appear.
+
+# What message will eventually appear in the sky?
+
+import re
+from operator import itemgetter
+
+import numpy as np
+
+with open("files/P10.txt") as f:
+    points = [tuple(map(int, re.findall(r"-?\d+", i))) for i in f]
+
+points_arr = np.array(points)
+
+
+def is_complete_row(line):
+    """Assumming that a line will have, at least, 10 points in the same row"""
+    return len(set(np.array(sorted(line, key=itemgetter(0)))[:10, 0])) == 1
+
+
+def find_time(arr):
+    # get position and velocity arrays
+    pos = arr[:, :2]
+    vel = arr[:, 2:]
+
+    found = False
+    cnt = 0
+    while not found:
+        pos += vel
+        cnt += 1
+        if is_complete_row(pos):
+            found = True
+            return cnt
+
+
+message_time = find_time(points_arr)