2022: d25: ex1: add solution

2022/d25/ex1/ex1.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+
+import sys
+
+
+def solve(input: list[str]) -> str:
+    def from_snafu(input: str) -> int:
+        res = 0
+        for c in input:
+            if c == "=":
+                n = -2
+            elif c == "-":
+                n = -1
+            else:
+                n = int(c)
+            res = res * 5 + n
+        return res
+
+    def to_snafu(input: int) -> str:
+        # Base case
+        if not input:
+            return "0"
+
+        DIGITS = {
+            2: "2",
+            1: "1",
+            0: "0",
+            -1: "-",
+            -2: "=",
+        }
+
+        digits: list[int] = []
+        while input:
+            input, d = divmod(input, 5)
+            if d not in DIGITS:
+                d -= 5
+                input += 1
+            digits.append(d)
+        return "".join(DIGITS[c] for c in reversed(digits))
+
+    return to_snafu(sum(map(from_snafu, input)))
+
+
+def main() -> None:
+    input = sys.stdin.read().splitlines()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()