Day 16

day16/part1.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+import re
+
+
+def yield_spans(gs: dict):
+    for g in gs.values():
+        yield g[:2]
+        yield g[2:]
+
+
+def in_spans(x, spans):
+    for span in spans:
+        if span[0] <= x <= span[1]:
+            return True
+    return False
+
+
+lines = (x.strip() for x in open("input.txt"))
+REGEX_RANGES = re.compile(r"^([a-z ]+): (\d+)-(\d+) or (\d+)-(\d+)$")
+groups = {}
+your = ()
+nearby = []
+read_step = 0
+
+for line in lines:
+    if read_step == 0:
+        if line == "":
+            read_step = 1
+            continue
+        match = REGEX_RANGES.match(line)
+        groups[match[1]] = list(map(int, match.groups()[1:]))
+    elif read_step == 1:
+        if line == "":
+            read_step = 2
+            continue
+        if line.startswith("your"):
+            continue
+        your = list(map(int, line.split(',')))
+    elif read_step == 2:
+        if line.startswith("nearby"):
+            continue
+        nearby.append(list(map(int, line.split(','))))
+
+valid_spans = []
+for span in yield_spans(groups):
+    start_idx = next((i for i, v in enumerate(valid_spans) if span[0] <= v[1]), len(valid_spans))
+    end_idx = next((len(valid_spans)-i for i, v in enumerate(valid_spans[::-1]) if span[1] >= v[0]), 0)
+    for idx in range(start_idx, end_idx):
+        popped = valid_spans.pop(start_idx)
+        span = (min(popped[0], span[0]), max(popped[1], span[1]))
+    valid_spans.insert(start_idx, tuple(span))
+
+print("Valid Spans:", valid_spans)
+
+
+invalid_sum = sum(x for n in nearby for x in n if not in_spans(x, valid_spans))
+print(invalid_sum)