LeetCode #8 String to Integer (atoi)

Yup, It’s basically like a meat grinder 🍖🥩 🍗

Introduction

Hey, there fellow reader! Looking for an in depth explanation to this seemingly easy LeetCode problem. Awesome 😎 , you came to the right place! My method is pretty standard 4 step aproach. I’ll read the prompt & examples, share my thoughts & take notes, Then will build out a solution step by step. Finally I’ll provide the solution and a take away.

Let’s jump into the fray…

Prompt & Examples

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function).

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++'s atoi function). The algorithm for myAtoi(string s) is as follows:

  1. Read in and ignore any leading whitespace.
  2. Check if the next character (if not already at the end of the string) is '-' or '+'. Read this character in if it is either. This determines if the final result is negative or positive respectively. Assume the result is positive if neither is present.
  3. Read in next the characters until the next non-digit charcter or the end of the input is reached. The rest of the string is ignored.
  4. Convert these digits into an integer (i.e. "123" -> 123, "0032" -> 32). If no digits were read, then the integer is 0. Change the sign as necessary (from step 2).
  5. If the integer is out of the 32-bit signed integer range [-231, 231 - 1], then clamp the integer so that it remains in the range. Specifically, integers less than -231 should be clamped to -231, and integers greater than 231 - 1 should be clamped to 231 - 1.
  6. Return the integer as the final result.
  7. Return the integer as the final result.

First Thoughts

Building out the Solution

You may notice that I used a meat grinder, which is exactly what we are dealing with here. We are given an input(meat), an empty function(the machine), and ground beef coming out the other end (solution). That’s exactly how i’d like to solve this problem. The key here is understanding what’s suppose to go under the hood. So let’s use some deduction and clues to build out this grinder!

Conclusion

Links

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