2017: d03: ex1: add solution

2017/d03/ex1/ex1.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+
+import itertools
+import sys
+from typing import NamedTuple
+
+
+class Point(NamedTuple):
+    x: int
+    y: int
+
+
+def solve(input: str) -> int:
+    def target_coord(target: int) -> Point:
+        for dist in itertools.count():
+            side = dist * 2 + 1
+            bot_right = side * side
+            if bot_right < target:
+                continue
+            # Target must be in the last loop, before bot_right
+            bot_left = bot_right - side + 1
+            top_left = bot_left - side + 1
+            top_right = top_left - side + 1
+            if bot_left <= target <= bot_right:
+                return Point(dist - (bot_right - target), -dist)
+            if top_left <= target <= bot_left:
+                return Point(-dist, -dist + (bot_left - target))
+            if top_right <= target <= top_left:
+                return Point(-dist + (top_left - target), dist)
+            if target <= top_right:
+                return Point(dist, dist - (top_right - target))
+            assert False  # Sanity check
+        assert False  # Sanity check
+
+    target = int(input)
+    coord = target_coord(target)
+    return abs(coord.x) + abs(coord.y)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()