Code RoomDecode ways
MediumPrep Room Coding #1611

Decode ways

CodingAlgorithms & data structuresMid–Senior~25 min

A message of digits is encoded where 'A'..'Z' map to '1'..'26'. Return the number of ways to decode it.

Implement
num_decodings(s: str) → int
Examples
in["12"]out2
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

0:00 of about 25 min
InputExpectedGot
["12"]2not run yetsample