How to Solve Replace All Digits with Characters Problem

You are given a 0-indexed string s that has lowercase English letters in its even indices and digits in its odd indices. You must perform an operation shift(c, x), where c is a character and x is a digit, that returns the xth character after c. For every odd index i, you want to replace the digit s[i] with the result of the shift(s[i-1], s[i]) operation. Return s after replacing all digits. It is guaranteed that shift(s[i-1], s[i]) will never exceed 'z'. Note that shift(c, x) is not a preloaded function, but an operation to be implemented as part of the solution.