String to Integer (atoi) Leetcode Solution

String to Integer (atoi) :

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 character 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.
  • Only the space character ‘ ‘ is considered a whitespace character.
  • Do not ignore any characters other than the leading whitespace or the rest of the string after the digits.

String to Integer (atoi) Leetcode Solution:

Constraints :

  • 0 <= s.length <= 200
  • s consists of English letters (lower-case and upper-case), digits (0-9), ‘ ‘, ‘+’, ‘-‘, and ‘.’.

Example 2 :

  • Input: s = ” -42″
  • Output: -42
  • Explanation:
    Step 1: ” -42″ (leading whitespace is read and ignored)
    Step 2: ” -42″ (‘-‘ is read, so the result should be negative)
    Step 3: ” -42″ (“42” is read in)
    The parsed integer is -42.
    Since -42 is in the range [-231, 231 – 1], the final result is -42.

Approach for Longest Palindromic Substring LeetCode Solution : 

  1. Check if string is empty or not.
  2. Check for spaces and then remove them.
  3. Check for “-“, “+”(store “-“).
  4. If again encounter space or alphabet then exit the loop.
  5. Store the integer.
  6. Check if the sotred value is less than INT_MIN or greater than INT_MAX.
  7. Return the product of sign and the stored value.

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Code for String to integer (atoi) LeetCode Solution :

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