Day 15

day15/input.txt

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+Sensor at x=1384790, y=3850432: closest beacon is at x=2674241, y=4192888
+Sensor at x=2825953, y=288046: closest beacon is at x=2154954, y=-342775
+Sensor at x=3553843, y=2822363: closest beacon is at x=3444765, y=2347460
+Sensor at x=2495377, y=3130491: closest beacon is at x=2761496, y=2831113
+Sensor at x=1329263, y=1778185: closest beacon is at x=2729595, y=2000000
+Sensor at x=2882039, y=2206085: closest beacon is at x=2729595, y=2000000
+Sensor at x=3903141, y=2510440: closest beacon is at x=4006219, y=3011198
+Sensor at x=3403454, y=3996578: closest beacon is at x=3754119, y=4475047
+Sensor at x=3630476, y=1048796: closest beacon is at x=3444765, y=2347460
+Sensor at x=16252, y=2089672: closest beacon is at x=-276514, y=2995794
+Sensor at x=428672, y=1150723: closest beacon is at x=-281319, y=668868
+Sensor at x=2939101, y=3624676: closest beacon is at x=2674241, y=4192888
+Sensor at x=3166958, y=2890076: closest beacon is at x=2761496, y=2831113
+Sensor at x=3758241, y=3546895: closest beacon is at x=4006219, y=3011198
+Sensor at x=218942, y=3011070: closest beacon is at x=-276514, y=2995794
+Sensor at x=52656, y=3484635: closest beacon is at x=-276514, y=2995794
+Sensor at x=2057106, y=405314: closest beacon is at x=2154954, y=-342775
+Sensor at x=1966905, y=2495701: closest beacon is at x=2761496, y=2831113
+Sensor at x=511976, y=2696731: closest beacon is at x=-276514, y=2995794
+Sensor at x=3094465, y=2478570: closest beacon is at x=3444765, y=2347460
+Sensor at x=806671, y=228252: closest beacon is at x=-281319, y=668868
+Sensor at x=3011731, y=1976307: closest beacon is at x=2729595, y=2000000

day15/part1.py

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+#!/usr/bin/env python3
+import re
+
+lines = (x.strip() for x in open("input.txt"))
+target = 2000000
+intervals = []
+known_targets = set()
+
+for line in lines:
+    x, y, a, b = map(int, re.search(r"(-?\d+).+?(-?\d+).+?(-?\d+).+?(-?\d+)", line).groups())
+    dist = abs(x-a) + abs(y-b)
+    width = dist-abs(y-target)
+    if width >= 0:
+        intervals.append((x-width, x+width))
+    if b == target:
+        known_targets.add(a)
+    if y == target:
+        known_targets.add(x)
+
+
+intervals.sort(key=lambda x: x[0])
+merged = [intervals[0]]
+for i in intervals[1:]:
+    if merged[-1][1] >= i[0]:
+        merged[-1] = (merged[-1][0], max(merged[-1][1], i[1]))
+    else:
+        merged.append(i)
+
+print(sum(b-a+1 for a, b in merged)-len(known_targets))

day15/part2.py

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+#!/usr/bin/env python3
+import re
+
+lines = (x.strip() for x in open("input.txt"))
+lines = [tuple(map(int, re.search(r"(-?\d+).+?(-?\d+).+?(-?\d+).+?(-?\d+)", line).groups())) for line in lines]
+
+for target in range(0, 4000000): #3186981
+    if target % 40000 == 0:
+        print(target/4000000)
+    intervals = []
+    known_targets = set()
+
+    for line in lines:
+        x, y, a, b = line
+        dist = abs(x-a) + abs(y-b)
+        width = dist-abs(y-target)
+        if width >= 0:
+            intervals.append((x-width, x+width))
+        if b == target:
+            known_targets.add(a)
+        if y == target:
+            known_targets.add(x)
+
+
+    intervals.sort(key=lambda x: x[0])
+    merged = [intervals[0]]
+    for i in intervals[1:]:
+        if merged[-1][1] >= i[0]:
+            merged[-1] = (merged[-1][0], max(merged[-1][1], i[1]))
+        else:
+            merged.append(i)
+
+    if len(merged) > 1:
+        print(target, merged, (merged[0][1]+1)*4000000+target)
+        break