String to Integer (atoi)

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Description

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer.

The algorithm for myAtoi(string s) is as follows:

- Whitespace: Ignore any leading whitespace (" ").

- Signedness: Determine the sign by checking if the next character is '-' or '+', assuming positivity if neither present.

- Conversion: Read the integer by skipping leading zeros until a non-digit character is encountered or the end of the string is reached. If no digits were read, then the result is 0.

- Rounding: If the integer is out of the 32-bit signed integer range [-2³¹, 2³¹ - 1], then round the integer to remain in the range. Specifically, integers less than -2³¹ should be rounded to -2³¹, and integers greater than 2³¹ - 1 should be rounded to 2³¹ - 1.

Return the integer as the final result.

Example 1:

The underlined characters are what is read in and the caret is the current reader position.

Step 1: "42" (no characters read because there is no leading whitespace)

Step 2: "42" (no characters read because there is neither a '-' nor '+')

Step 3: "42" ("42" is read in)

Example 2:

Step 1: " -042" (leading whitespace is read and ignored)

Step 2: " -042" ('-' is read, so the result should be negative)

Step 3: " -042" ("042" is read in, leading zeros ignored in the result)

Example 3:

Step 1: "1337c0d3" (no characters read because there is no leading whitespace)

Step 2: "1337c0d3" (no characters read because there is neither a '-' nor '+')

Step 3: "1337c0d3" ("1337" is read in; reading stops because the next character is a non-digit)

Example 4:

Step 1: "0-1" (no characters read because there is no leading whitespace)

Step 2: "0-1" (no characters read because there is neither a '-' nor '+')

Step 3: "0-1" ("0" is read in; reading stops because the next character is a non-digit)

Solution