• https://leetcode.com/problems/string-to-integer-atoi/description/

• Implement atoi to convert a string to an integer.

Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.

Notes:

• It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.

• The function first discards as many whitespace characters as necessary until the first non-whitespace character is found.
• Then, starting from this character, takes an optional initial plus or minus sign followed by as many numerical digits as possible, and interprets them as a numerical value.
• The string can contain additional characters after those that form the integral number, which are ignored and have no effect on the behavior of this function.
• If the first sequence of non-whitespace characters in str is not a valid integral number, or if no such sequence exists because either str is empty or it contains only whitespace characters, no conversion is performed.
• If no valid conversion could be performed, a zero value is returned. If the correct value is out of the range of representable values, INT_MAX (2147483647) or INT_MIN (-2147483648) is returned.

You can examine a possible solution in string_to_integer.py