Decode Ways
Difficulty: Medium
Source: LeetCode
Description
Given a string s of digits, return the number of ways to decode it using the mapping:
"1" -> 'A',
"2" -> 'B',
...,
"26" -> 'Z'
A digit string can be decoded in multiple ways since some codes overlap (e.g., "12" can be "AB" or "L").
Rules:
- Valid codes are "1" to "26"
- Leading zeros are invalid (e.g., "06" is invalid, but "6" is valid)
- Return
0if the string cannot be decoded
Examples
Input: s = "12"
Output: 2
Explanation: Can be decoded as "AB" (1, 2) or "L" (12)
Input: s = "11106"
Output: 2
Explanation:
- "AAJF" with grouping (1, 1, 10, 6)
- "KJF" with grouping (11, 10, 6)
- (1, 11, 06) is invalid because "06" is not valid
Code
# To be solved