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String to Integer (atoi)

medium
Acceptance: 41%
Strings

Write a function that parses a string and extracts an integer from it, mimicking simplified integer-parsing behavior. The function should skip leading whitespace, recognize an optional '+' or '-' sign, then read consecutive digit characters. Convert the resulting digit sequence to an integer. If the value exceeds the 32-bit signed integer range [-2^31, 2^31 - 1], clamp it to the nearest boundary.

Examples

Example 1:
Input:s = " 123"
Output:123
Explanation: Leading spaces are ignored and the digits '123' are parsed as the integer 123.
Example 2:
Input:s = "-98abc"
Output:-98
Explanation: After the sign '-', digits '98' are consumed. Parsing stops at the non-digit character 'a'.

Hints

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class Solution {
    public int myAtoi(String s) {
        int i = 0, n = s.length(), sign = 1;
        long result = 0;
        while (i < n && s.charAt(i) == ' ') i++;
        if (i < n && (s.charAt(i) == '+' || s.charAt(i) == '-')) {
            sign = s.charAt(i) == '-' ? -1 : 1;
            i++;
        }
        while (i < n && Character.isDigit(s.charAt(i))) {
            result = result * 10 + (s.charAt(i) - '0');
            if (result * sign > Integer.MAX_VALUE) return Integer.MAX_VALUE;
            if (result * sign < Integer.MIN_VALUE) return Integer.MIN_VALUE;
            i++;
        }
        return (int)(result * sign);
    }
}
Time complexityO(n)
Space complexityO(1)