Add 2022 solutions

2022/d15.py

@@ -0,0 +1,151 @@
+import lib
+import math
+
+EXAMPLE = """
+Sensor at x=2, y=18: closest beacon is at x=-2, y=15
+Sensor at x=9, y=16: closest beacon is at x=10, y=16
+Sensor at x=13, y=2: closest beacon is at x=15, y=3
+Sensor at x=12, y=14: closest beacon is at x=10, y=16
+Sensor at x=10, y=20: closest beacon is at x=10, y=16
+Sensor at x=14, y=17: closest beacon is at x=10, y=16
+Sensor at x=8, y=7: closest beacon is at x=2, y=10
+Sensor at x=2, y=0: closest beacon is at x=2, y=10
+Sensor at x=0, y=11: closest beacon is at x=2, y=10
+Sensor at x=20, y=14: closest beacon is at x=25, y=17
+Sensor at x=17, y=20: closest beacon is at x=21, y=22
+Sensor at x=16, y=7: closest beacon is at x=15, y=3
+Sensor at x=14, y=3: closest beacon is at x=15, y=3
+Sensor at x=20, y=1: closest beacon is at x=15, y=3
+"""
+
+def unify_ranges(ranges):
+    # aaaaaaaaaaa
+    #     bbbb
+    #
+    # aaa
+    #     bbb
+    #
+    # aaa
+    #   bbb
+    ranges = sorted(ranges)
+    while True:
+        for i in range(len(ranges) - 1):
+            a, b = ranges[i], ranges[i + 1]
+            if a == b:
+                del ranges[i]
+                break
+            elif a[0] == b[0]:
+                ranges[i] = (a[0], max(a[1], b[1]))
+                del ranges[i + 1]
+                break
+            elif a[1] == b[1]:
+                ranges[i] = (min(a[0], b[0]), b[1])
+                del ranges[i + 1]
+                break
+            elif a[0] < b[0] and a[1] > b[1]:
+                del ranges[i + 1]
+                break
+            elif a[0] > b[0] and a[1] < b[1]:
+                del ranges[i]
+                break
+            elif a[1] < b[0]:
+                pass
+            elif a[0] <= b[1] and a[1] >= b[0]:
+                ranges[i] = (a[0], b[1])
+                del ranges[i + 1]
+                break
+            else:
+                raise Exception("uhoh", a, b)
+        else:
+            return ranges
+    return ranges
+
+def mdist(dx, dy):
+    return abs(dx) + abs(dy)
+
+def xdist(dm, dy):
+    x = dm - abs(dy)
+    if x <= 0:
+        return 0
+    return x
+
+def solve(lines: list[str], yt):
+    sensors = []
+    bacons = set()
+    for (i, line) in enumerate(lines):
+        digits = lib.str_to_ints(line)
+        sx, sy, bx, by = digits
+        sm = mdist(bx - sx, by - sy)
+        sensors.append([sx, sy, sm])
+        bacons.add((bx, by))
+
+    ranges = []
+    for (sx, sy, sm) in sensors:
+        x_range = xdist(sm, yt - sy)
+        if x_range == 0:
+            continue
+        r = (sx - x_range, sx + x_range)
+        # print(f"{sx=} {sy=} {r=}")
+        ranges.append(r)
+
+    ranges = unify_ranges(ranges)
+    r = 0
+    for (a, b) in ranges:
+        r += b - a + 1
+        for (bx, by) in list(bacons):
+            if by == yt and bx >= a and bx <= b:
+                r -= 1
+    # 140:00 I don't know what a Manhattan distance is.
+    return r
+
+def solve2(lines: list[str], xymax):
+    sensors = []
+    bacons = set()
+    for (i, line) in enumerate(lines):
+        digits = lib.str_to_ints(line)
+        sx, sy, bx, by = digits
+        sm = mdist(bx - sx, by - sy)
+        sensors.append([sx, sy, sm])
+        bacons.add((bx, by))
+
+    finds = []
+    for yt in range(0, xymax):
+        ranges = []
+        for (sx, sy, sm) in sensors:
+            x_range = xdist(sm, yt - sy)
+            if x_range == 0:
+                continue
+            r = (sx - x_range, sx + x_range)
+            ranges.append(r)
+        ranges = unify_ranges(ranges)
+
+        if ranges[0][0] > 0:
+            raise Exception("Bacon at 0.")
+        elif ranges[-1][-1] < xymax:
+            raise Exception("Bacon at xymax.")
+
+        for i in range(len(ranges) - 1):
+            if ranges[i + 1][0] - ranges[i][1] > 1:
+                finds.append((ranges[i][1] + 1, yt))
+    if len(finds) != 1:
+        raise Exception("TOO MANY FINDS")
+    else:
+        x, y = finds[0]
+        return x * 4000000 + y
+    # 10:00
+
+def main():
+    lines = lib.str_to_lines_no_empty(EXAMPLE)
+    print("Example  1:", solve(lines, 10))
+
+    lines = lib.str_to_lines_no_empty(open("d15.txt").read())
+    print("Solution 1:", solve(lines, 2000000))
+
+    lines = lib.str_to_lines_no_empty(EXAMPLE)
+    print("Example  2:", solve2(lines, 20))
+
+    lines = lib.str_to_lines_no_empty(open("d15.txt").read())
+    print("Solution 2:", solve2(lines, 4000000))
+
+if __name__ == "__main__":
+    main()