Disclaimer: Here is the practice link to help you assess your knowledge better. It's highly recommend trying to solve it before looking at the solution.

Approach

Algorithm

Ignore any leading whitespace to find where the number actually begins.
Determine if the number is meant to be positive or negative by checking the sign symbol.
Scan the digits one by one to build the number progressively from left to right.
Each new digit contributes to the overall number by shifting the previous digits left (base 10).
Watch for overflow by checking before each addition whether the next step would exceed integer limits.
Once digit parsing ends, apply the sign and return the final result.