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Unique-digits integers in a range

ISC 2007 Computer Science Practical, Question 3 · Number programs

The question

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, write a program to determine how many unique-digit integers are there in the range between m and n (both inclusive) and output them.

The input contains two positive integers m and n. Assume m < 30000 and n < 30000. You are to output the number of unique-digit integers in the specified range along with their values in the format specified below:

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 IN INTEGERS IS : 9

INPUT:  m  =  2500
        n  =  2550
OUTPUT: THE UNIQUE-DIGIT INTEGERS ARE:-
        2501, 2503, 2504, 2506, 2507, 2508, 2509, 2510, 2513, 2514, 2516, 2517, 2518, 2519, 2530, 2531, 2534, 2536, 2537, 2538, 2539, 2540, 2541, 2543, 2546, 2547, 2548, 2549.
        FREQUENCY OF UNIQUE-DIGIT INTEGERS IS : 28

Question: ISC 2007 Computer Science Paper 2 (Practical), Question 3, set by the Council for the Indian School Certificate Examinations (CISCE). Solution and video: Vinay Singh.

Java solution

ISC2007Q3.java Download GitHub

import java.util.*;

class Unique{
    private int m,n,frequency;
    private String output;
    public Unique(int m, int n){
        this.m=m;
        this.n=n;
        findUniqueDigitNumbers();
    }
    public void findUniqueDigitNumbers(){
        frequency=0;
        output="THE UNIQUE-DIGIT INTEGERS ARE:-\n\t";
        for( int i=m; i<=n; i++){
            if(isUniqeNumber(i)){
                frequency++;
                output+=i+", ";
            }
        }
        output=output.substring(0, output.length()-2)+".";
    }
    private boolean isUniqeNumber(int n){
        boolean unique[] = new boolean[10];
        int digit;
        for( int temp=n;temp>0; temp/=10){
            digit=temp%10;
            if( unique[digit]) return false;
            unique[digit]=true;
        }
        return true;
    }
    public String toString(){
        return output;
    }
    public int getFrequency(){
        return frequency;
    }
}
class ISC2007Q3 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.print("INPUT:\tm = ");
        int m = in.nextInt();
        System.out.print("\tn = ");
        int n = in.nextInt();
        Unique obj = new Unique(m,n);
        System.out.println("OUTPUT:"+obj);
        System.out.println("FREQUENCY OF UNIQUE-DIGIT IN INTEGERS IS : "+obj.getFrequency());
        in.close();
    }
}

Unique-digits integers in a range

The question

Java solution

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