2024 Day 2 Part 2

2024/src/day02.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+
+import os
+
+
+def relpath(path: str) -> str:
+    return os.path.join(os.path.dirname(__file__), path)
+
+
+reports = []
+with open(relpath("../input/day02.txt")) as f:
+    for line in f.readlines():
+        report = [int(i) for i in line.strip().split()]
+        reports.append(report)
+
+Report = list[int]
+
+
+def sign(x: int) -> int:
+    if x > 0:
+        return +1
+    if x < 0:
+        return -1
+    return 0
+
+
+def is_safe(report: Report) -> bool:
+    return first_problem(report) is None
+
+
+def first_problem(report: Report) -> int | None:
+    direction = sign(report[1] - report[0])
+    for i, (prev, next) in enumerate(zip(report[:-1], report[1:])):
+        diff = next - prev
+        if direction != sign(diff) or abs(diff) < 1 or abs(diff) > 3:
+            return i
+
+
+def is_safe_tolerant(report: Report) -> bool:
+    if is_safe(report):
+        return True
+
+    for i in range(len(report)):
+        if is_safe(report[:i] + report[i+1:]):
+            return True
+
+    return False
+
+
+n = 0
+m = 0
+for report in reports:
+    if is_safe(report):
+        n += 1
+    if is_safe_tolerant(report):
+        m += 1
+
+print(n)
+print(m)