Add 2023 solutions

2023/d9.py

@@ -0,0 +1,53 @@
+import lib
+
+EXAMPLE = """
+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45
+"""
+
+def solve(lines: list[str]):
+    res = 0
+    for (i, line) in enumerate(lines):
+        digits = lib.str_to_ints(line)
+        last_digits = []
+        while not all(d == 0 for d in digits):
+            last_digits.append(digits[-1])
+            digits = [digits[i + 1] - digits[i] for i in range(len(digits) - 1)]
+        s = 0
+        for d in reversed(last_digits):
+            s = s + d
+        res += s
+    # 50:00 ... problem in my helper function... lol
+    return res
+
+def solve2(lines: list[str]):
+    res = 0
+    for (i, line) in enumerate(lines):
+        digits = lib.str_to_ints(line)
+        first_digits = []
+        while not all(d == 0 for d in digits):
+            first_digits.append(digits[0])
+            digits = [digits[i + 1] - digits[i] for i in range(len(digits) - 1)]
+        s = 0
+        for d in reversed(first_digits):
+            s = d - s
+        res += s
+    # 57:00...
+    return res
+
+def main():
+    lines = lib.str_to_lines_no_empty(EXAMPLE)
+    print("Example  1:", solve(lines))
+
+    lines = lib.str_to_lines_no_empty(open("d9.txt").read())
+    print("Solution 1:", solve(lines))
+
+    lines = lib.str_to_lines_no_empty(EXAMPLE)
+    print("Example  2:", solve2(lines))
+
+    lines = lib.str_to_lines_no_empty(open("d9.txt").read())
+    print("Solution 2:", solve2(lines))
+
+if __name__ == "__main__":
+    main()