Optimal Approach

Algorithm

Instead of converting the integer into a string, we work directly with the digits using arithmetic. We extract each digit from the number by repeatedly taking the remainder when divided by 10. If the digit is 0, we change it to 1. We then rebuild the number in reverse and reverse it again to get the final result.

Initialize a new number to hold the result
Loop while the original number is greater than 0
Extract the last digit using remainder operation
If the digit is 0, treat it as 1
Append the digit to the result number using multiplication and addition
After the loop, reverse the result to maintain original digit order
Return the final reversed result