Solve 2021 day 4 and 5

2021/d5.py

@@ -0,0 +1,39 @@
+from lib import get_data
+from lib import ints
+from collections import defaultdict
+
+data = get_data(__file__).strip()
+
+counts = defaultdict(int)
+for line in data.splitlines():
+    x1, y1, x2, y2 = ints(line)
+    if x1 == x2 or y1 == y2:
+        if x1 == x2:
+            for y in range(min(y1, y2), max(y1, y2) + 1):
+                counts[(x1, y)] += 1
+        elif y1 == y2:
+            for x in range(min(x1, x2), max(x1, x2) + 1):
+                counts[(x, y1)] += 1
+        else:
+            assert False
+
+r = sum(1 for v in counts.values() if v > 1)
+print(r)
+
+
+for line in data.splitlines():
+    x1, y1, x2, y2 = ints(line)
+    if x1 == x2 or y1 == y2:
+        pass
+    else:
+        dx = 1 if x2 > x1 else -1
+        dy = 1 if y2 > y1 else -1
+
+        while (x1, y1) != (x2, y2):
+            counts[(x1, y1)] += 1
+            x1 += dx
+            y1 += dy
+        counts[(x2, y2)] += 1
+
+r = sum(1 for v in counts.values() if v > 1)
+print(r)