A message containing letters from A-Z can be encoded into numbers using the mapping: 'A' -> "1", 'B' -> "2", ... 'Z' -> "26". To decode an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping above. Given a string s containing only digits, return the number of ways to decode it.
Java
Decode Ways
A message containing letters from A-Z can be encoded into numbers using the mapping: 'A' -> "1", 'B' -> "2", ... 'Z' -> "26". To decode an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping above. Given a string s containing only digits, return the number of ways to decode it.