Duck Number in JAVA

Duck Number

Duck Number : A Duck number is a number which has zeroes present in it, but there should be no zero present in the beginning of the number. 

For example : 3210, 7056, 8430709 are all duck numbers, whereas 08237, 04309, 2357,1253 etc are not.

Input     : 50401

Output  : It is a Duck Number

Input     : 04208

Output  : It is not a Duck Number

Input     : 4231

Output  : It is not a Duck Number

Algorithm and Program given below :-

Algorithm :-

• Input a number in a string variable
• In a variable find its length
• Using if statement check if it has 0 at 1st position (i.e. at 0th position in string) using "charAt"
• If it has 0 than display "It is not a duck number"
• Else using for loop extract each character from 2nd position (i.e. at 1st position of string).
• Now check if the character is '0' or not 
• If it is '0' than use break statement and display "It is Duck Number"
• Else display "It is not a Duck Number"

Program :-

import java.io.*;
import java.util.*;
class Duck
{
    public static void main(String args[])
    {    
        Scanner in = new Scanner(System.in);
        String str;
        char ch;
        int k=0,l,i;
        System.out.println("Enter Number ");
        str= in.nextLine(); // Input number as a String
        l= str.length(); // storing length of the number
        if(str.charAt(0)=='0') // if at 0th position 0 is present
        {
            System.out.println("It is not a Duck Number "+str); // print number is not duck no.
        }
        else
        {
            for(i=1;i<l;i++)
            {
                ch=str.charAt(i); //extracting each character from 1st position
                if(ch=='0') // if is found at any position
                {
                    k=1; //defining value of k=1
                    break;
                }
            }
            if(k==1)
            {
                System.out.println("It is a Duck Number : "+str); //printing duck number
            }
            else
            {
                System.out.println("It is not a Duck Number : "+str); // printing not a duck no.
            }
        }
    } // end of main method
} // end of class

All the Best :)

Keep Learning :)

Watch this Program Video : https://youtu.be/OQVCBIxjBP4