2021: d10: ex1: add solution

2021/d10/ex1/ex1.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+
+import sys
+from typing import List, Optional, cast
+
+
+def solve(input: List[str]) -> int:
+    def find_illegal_char(input: str) -> Optional[int]:
+        chunks: List[str] = []
+        ends_to_start = {
+            ")": "(",
+            "]": "[",
+            "}": "{",
+            ">": "<",
+        }
+
+        for i, c in enumerate(input):
+            # Is it a chunk beginning
+            if c not in ends_to_start:
+                chunks.append(c)
+                continue
+            # Is it matching the last element on the chunk stack
+            current = chunks.pop()
+            # If not, corruption has been found
+            if ends_to_start[c] != current:
+                return i
+
+        return None
+
+    score = {
+        ")": 3,
+        "]": 57,
+        "}": 1197,
+        ">": 25137,
+    }
+
+    return sum(
+        score[line[cast(int, find_illegal_char(line))]]
+        for line in input
+        if find_illegal_char(line) is not None
+    )
+
+
+def main() -> None:
+    input = [line.strip() for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()