aoc 2025 1+2

2025/02/Findings.md

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+# Day 02
+
+## Part 1
+
+Again, quite easy.
+
+## Part 2
+
+As the genral rule of thumb in AoC, now lets generalize. I had more of a brute force approach with a few tricks than an actual nice solution tbh.
+
+Actually finding recurring patterns sounds like something a FFT should be good at.

2025/02/main.py

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+def calc_1(ids: list[tuple[int, int]]):
+    invalid = 0
+    for i in ids:
+        for x in range(i[0], i[1] + 1):
+            asStr = str(x)
+            l = len(asStr)
+            isEvenLength = l % 2 == 1
+            if isEvenLength:
+                continue
+            half = l // 2
+            if asStr[:half] == asStr[half:]:
+                invalid += x
+    return invalid
+
+
+def calc_2(ids: list[tuple[int, int]]):
+    invalid = 0
+    for i in ids:
+        for x in range(i[0], i[1] + 1):
+            s = str(x)
+            l = len(s)
+            for m in range(1, (l // 2) + 1):
+                if l % m != 0:
+                    continue
+                first = s[:m]
+                max_multiples = l // m
+                is_invalid = False
+                for offset in range(1, max_multiples):
+                    start = offset * m
+                    end = start + m
+                    if first != s[start:end]:
+                        is_invalid = True
+                        break
+                if is_invalid:
+                    continue
+                invalid += x
+                break
+    return invalid
+
+
+def parse(raw):
+    ids = raw.read().strip().replace("\n", "").split(",")
+    return [tuple(map(int, (i.split("-")))) for i in ids]
+
+
+# Run
+with open("./2025/02/train.txt") as f:
+    d = parse(f)
+    print(f"Train 1: {calc_1(d)}")
+    print(f"Train 2: {calc_2(d)}")
+
+with open("./2025/02/data.txt") as f:
+    d = parse(f)
+    print(f"Actual 1: {calc_1(d)}")
+    print(f"Actual 2: {calc_2(d)}")