Solution: String to Integer (atoi)

Statement

Write a function, myAtoi(string s), that converts a string to a 32–bit signed integer. It is equivalent to the atoi function in C/C++.

The myAtoi function reads the input string, s, from left to right for the conversion process. The conversion begins by removing any leading whitespace. Then, it checks if the next character is '+' or '-'. If it's '-', it implies that the result is negative, and there must be a '-' sign in front of the resulting integer. Otherwise, '+' implies that the result is positive, so there is no need to add a '+' sign in front of the resulting integer. For example, "-$25$" converts to -$25$, and "+$91$" converts to $91$. However, if neither is present, assume the result is positive.

After removing the whitespace, if the first non-space character is not a sign character, '+' or '-', but a non-digit character, i.e., an English letter or the period '$.$', the function stops processing further and returns $0$. For example, the strings "$\:\:\:$One$1$" and "$\:\:\:$$.5$" convert to $0$. Additionally, if the first non-space character is a sign character, '+' or '-', and the next character is a non-digit character (including the space character), the function returns $0$. For example, the strings "$\:\:\:$+$.23$ ...