[LeetCode] 7. Reverse Integer (Java)

• Reference

Solution

public class ReverseInteger {
    public static int reverse(int x) {
        long answer = 0;

        // 123 -> 12 (3)
        // 12 -> 1 (2)
        // 1 -> 0 (1)
        // x % 10 -> x / 10
        while (x != 0) {
            answer = answer * 10 + x % 10;
            x /= 10;
        }

        if (answer > Integer.MAX_VALUE || answer < Integer.MIN_VALUE ) {
            return 0;
        }

        return (int) answer;
    }

    public static void main(String[] args) {
        System.out.println(reverse(123));
        System.out.println(reverse(-123));
        System.out.println(reverse(120));
        System.out.println(reverse(1000000999));
    }
}