'A'→1, 'B'→2, ..., 'Z'→26. Given a string of digits, return the number of ways to decode it.
Input: s = '12'
Output: 2 ('AB' or 'L')
Input: s = '226'
Output: 3 ('BZ','VF','BBF')
Input: s = '06'
Output: 0Unlock hints progressively — start gentle, go deeper only if needed.
Level 1: Gentle Nudge
A subtle direction
Level 2: Approach
The algorithm to use
Level 3: Detailed
Step-by-step guidance
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