8. String to Integer (atoi)

Explanation:

To solve this problem, we need to follow the steps outlined in the problem description: ignoring leading whitespace, determining sign, converting the integer, and handling rounding. We can achieve this by iterating over the characters in the string and updating our result accordingly.

Trim leading whitespace.
Determine sign.
Convert the integer value.
Handle rounding for out-of-range values.

Time Complexity: O(n) where n is the length of the input string. Space Complexity: O(1)

:

View Leetcode Problem

class Solution {
    public int myAtoi(String s) {
        if (s.isEmpty()) return 0;

        int i = 0, sign = 1, result = 0;
        while (i < s.length() && s.charAt(i) == ' ') {
            i++;
        }

        if (i < s.length() && (s.charAt(i) == '+' || s.charAt(i) == '-')) {
            sign = (s.charAt(i) == '-') ? -1 : 1;
            i++;
        }

        while (i < s.length() && Character.isDigit(s.charAt(i))) {
            int digit = s.charAt(i) - '0';

            if (result > Integer.MAX_VALUE / 10 || (result == Integer.MAX_VALUE / 10 && digit > Integer.MAX_VALUE % 10)) {
                return (sign == 1) ? Integer.MAX_VALUE : Integer.MIN_VALUE;
            }

            result = result * 10 + digit;
            i++;
        }

        return result * sign;
    }
}

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