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y2022/p25.py

@@ -0,0 +1,29 @@
+def decode(string, swap={'1': 1, '=': -2, '-': -1, '0': 0, '2': 2}):
+    return sum(5 ** i * swap[c] for i, c in enumerate(string[::-1]))
+
+
+def base5(n):
+    ns = []
+    while n:
+        ns.append(n % 5)
+        n //= 5
+    return ns[::-1]
+
+
+def encode(n, swap={1: '1', -2: '=', -1: '-', 0: '0', 2: '2'}):
+    ms = []
+    carry = 0
+    for n in base5(n)[::-1]:
+        n += carry
+        if n > 2:
+            carry, value = 1, n % 3 - 2
+        else:
+            carry, value = 0, n
+        ms.append(swap[value])
+    if carry:
+        ms.append(swap[carry])
+    return ''.join(ms[::-1])
+
+
+n = sum(map(decode, open(0).read().splitlines()))
+print(encode(n))