Solution: Decode Ways
Explore how to solve the Decode Ways problem by determining the number of ways to decode a digit string into letters using dynamic programming. This lesson covers creating a DP array to store subproblem results, optimizing space usage, and understanding the logic behind one- and two-digit decoding. You'll develop a clear approach to break down and efficiently decode encoded messages.
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 ...