BlueJ Program on unique digit integer

BlueJ Program on unique digit integer

This BlueJ program was set in the ISC Computer Science Practical Examination of 2008.

The program is as follows:

A unique digit integer is a positive integer (without leading zeros) with no
duplicate digits. For example 7, 135,214 are all unique digit integers whereas 33,3121,300 are not.

Given two positive integers, m and n where m < n, write a program to determine how many unique digit integers are there in the range m and n (both inclusive)and display them.

Sample Data
Input:
m=100
n=120
Output:
The unique digit integers are:
102,103,104,105,106,107,108,109,120
Frequency of unique digit integers is : 9

import java.io.*;
class Digit
{
int k,x,i,j,m,n,c,arr[],index;
BufferedReader br;
public static void main(String args[])throws IOException
{
Digit ob=new Digit();
ob.take();
ob.show();
}
Digit()
{
br=new BufferedReader(new InputStreamReader(System.in));
arr=new int[1000];
c=0;
index=0;
}
public void take()throws IOException
{
while(true)
{
System.out.println("Enter the Lower range:");
m=Integer.parseInt(br.readLine().trim());
System.out.println("Enter the Upper range:");
n=Integer.parseInt(br.readLine().trim());
if(m < n)
break;
}
}
void show ()
{
System.out.println("The unique digit integers are:");
for(i=m;i < =n;i++)
{
index=0;
for(j=i;j > 0;j=j/10)
{
x=j%10;
for(k=0;k < index;k++)
{
if (arr[k]==x)
break;
}
if(k < index)
break;
else
arr[index++]=x;
}
if (j==0)
{
c++;
System.out.print(" "+i);
}
}

System.out.println("\nFequency of unique digit integers is :"+ c);
}
}

Variable Descriptions of the unique digit integer program

‘m’ – This will hold the lower range
‘n’ – it will hold the upper range
‘i’, ‘j’, ‘k’ are loop control variables
‘x’ is used to hold digits
‘c’ is the counter to count unique digit numbers
‘arr[]’ is used to check the numbers for unique digits
‘index’ is the array index of the array ‘arr[]’
‘br’ BufferedReader class object

Algorithm of the unique digit integer program

Step 1: Take the lower range and store in ‘m’
Step 2: Take the upper range and store in ‘n’
Step 3: If ‘m’ is not less than ‘n’ repeat steps 1 and 2, otherwise go to Step 4
Step 4: Repeat the following steps by assigning values starting from ‘m’ upto ‘n’ on ‘i’
Step 5: Set ‘0’ on ‘index’
Step 6: Assign the value of ‘i’ on ‘j and repeat the following steps until j becomes ‘0’
Step 7: Retrieve a digit from j and check whether it is present in the array ‘arr’
Step 8: If it is present, go to Step 4
Step 9: If not present assign the digit in the array ‘arr’ and increment ‘index’ by ‘1’
Step 10: Eliminate the digit from ‘j’ and go to Step &
Step 11: If ‘j’ becomes ‘0’, display the value of ‘I’ and increment ‘c’ by ‘1’
Step 12: Go to Step 4, if ‘I’ becomes greater than ‘n’ go to Step 13
Step 13: Display ‘c’