Solution: Decode Ways
Explore a dynamic programming method to decode digit-only strings into possible letter combinations. This lesson guides you through an efficient algorithm that counts all valid decodings, improving space complexity by using variable tracking instead of arrays. Learn how to handle constraints like invalid leading zeros and optimize your approach for coding interviews.
We'll cover the following...
Statement
Given a string that has only positive digits, your task is to decode the string and determine the number of possible ways to decode it.
Consider the input string as an encoded message, where each digit in the string represents an alphabet from A to Z. For reference, let’s look at the mapping below:
"1" represents "A"
"2" represents "B"
"3" represents "C"
"26" represents "Z"
How to perform the decode operation?
To decode an encoded message, we have to check whether or not each digit in the string can be mapped onto the mapping above. There can be multiple ways to decode a string.
For example, the string "231012" can be decoded in the ...