Question

4. Write a function to reverse an integer using numeric operators and without using any arrays or other data structures.
   The signature of the function is:
   int f(int n)

Examples

if the input integer is	return
1234	4321
12005	50021
1	1
1000	1
0	0
-12345	-54321

by java

Answer 1

public class ReverseIntegers {

    public int f(int n) {
        int sign = 1;
        if (n < 0) {
            sign = -1;
            n = -1 * n;
        }
        int rev = 0;
        while (n > 0) {
            rev *= 10;
            rev += n % 10;
            n /= 10;
        }
        return sign * rev;
    }

    public static void main(String[] args) {
        System.out.println(new ReverseIntegers().f(1234));
        System.out.println(new ReverseIntegers().f(12005));
        System.out.println(new ReverseIntegers().f(1));
        System.out.println(new ReverseIntegers().f(1000));
        System.out.println(new ReverseIntegers().f(0));
        System.out.println(new ReverseIntegers().f(-12345));
    }
}