2015 day 10

adventofcode/2015/day10/day10.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+import fileinput
+
+
+def look_and_say(seq):
+    """
+    Describe each element by counting the number of consecutive digits
+    of the same value and appending that count followed by the digit itself.
+    """
+    ret = []
+    current_char = seq[0]
+    current_count = 1
+    for c in seq[1:]:
+        if c == current_char:
+            current_count += 1
+        else:
+            ret.append(str(current_count))
+            ret.append(current_char)
+            current_char = c
+            current_count = 1
+
+    # last char
+    ret.append(str(current_count))
+    ret.append(current_char)
+    return "".join(ret)
+
+
+def main(inp):
+    inp = list(inp)
+    for _ in range(40):
+        inp = look_and_say(inp)
+    print("Part 1:", len(inp))
+
+    for _ in range(10):  # 40 + 10 = 50
+        inp = look_and_say(inp)
+    print("Part 2:", len(inp))
+
+
+if __name__ == "__main__":
+    lines = next(x.rstrip() for x in fileinput.input())
+    main(lines)