day 3

.gitignore

@@ -1 +1,2 @@
 *.in
+*.ex

day03.py

@@ -0,0 +1,28 @@
+import fileinput
+
+input = [s.strip() for s in fileinput.input()]
+part1, part2 = 0, 0
+
+
+def prio(x):
+    if x.islower():
+        return ord(x) - ord("a") + 1
+    else:
+        return ord(x) - ord("A") + 27
+
+
+for line in input:
+    first = set(line[: len(line) // 2])
+    second = set(line[len(line) // 2 :])
+    both = (first & second).pop()
+    part1 += prio(both)
+
+
+for i in range(0, len(input), 3):
+    x = set(input[i])
+    y = set(input[i + 1])
+    z = set(input[i + 2])
+    overlap = (x & y & z).pop()
+    part2 += prio(overlap)
+
+print(part1, part2)