Question

I just gave a coding interview on codility

I was asked the to implement the following, but i was not able to finish it in 20 minutes, now I am here to get ideas form this community

Write a function public int whole_cubes_count ( int A,int B ) where it should return whole cubes within the range

For example if A=8 and B=65, all the possible cubes in the range are 2^3 =8 , 3^3 =27 and 4^3=64, so the function should return count 3

I was not able to figure out how to identify a number as whole cube. How do I solve this problem?

A and B can have range from [-20000 to 20000]

This is what I tried

import java.util.Scanner;
class Solution1 {
  public int whole_cubes_count ( int A,int B ) {
      int count =0;

    while(A<=B)
    {
        double v = Math.pow(A, 1 / 3); // << What goes here?
        System.out.println(v);
        if (v<=B)
            {
            count=count+1;
            }
        A =A +1;
    }
    return count ;
  }

  public static void main(String[] args) 
  {
    System.out.println("Enter 1st Number");
    Scanner scan = new Scanner(System.in);
    int s1 = scan.nextInt();
    System.out.println("Enter 2nd Number");
    //Scanner scan = new Scanner(System.in);
    int s2 = scan.nextInt();
    Solution1 n = new Solution1();
     System.out.println(n.whole_cubes_count (s1,s2));
  }
}

Answer 1

Down and dirty, that’s what I say.

If you only have 20 minutes, then they shouldn’t expect super-optimized code. So don’t even try. Play to the constraints of the system which say only +20,000 to -20,000 as the range. You know the cube values have to be within 27, since 27 * 27 * 27 = 19683.

public int whole_cubes_count(int a, int b) {
    int count = 0;
    int cube;
    for (int x = -27; x <= 27; x++) {
        cube = x * x * x;
        if ((cube >= a) && (cube <= b))
            count++;
    }
    return count;
}