Integers from the range that are composed of a single distinct digit

Given two integer L and R representing a range [L, R], the task is to find the count of integers from the range that are composed of a single distinct digit.

Examples:

Input : L = 9, R = 11
Output : 2
Only 9 and 11 have single distinct digit

Input : L = 10, R = 50
Output : 4
11, 22, 33 and 44 are the only valid numbers


Naive Approach: Iterate through all the numbers and check if the number is composed of a single distinct digit only.

Below is the implementation of the above approach:

C++

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// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
  
// Boolean function to check
// distinct digits of a number
bool checkDistinct(int x)
{
    // Take last digit
    int last = x % 10;
  
    // Check if all other digits
    // are same as last digit
    while (x) {
        if (x % 10 != last)
            return false;
  
        // Remove last digit
        x = x / 10;
    }
  
    return true;
}
  
// Function to return the count of integers that
// are composed of a single distinct digit only
int findCount(int L, int R)
{
    int count = 0;
  
    for (int i = L; i <= R; i++) {
  
        // If i has single distinct digit
        if (checkDistinct(i))
            count += 1;
    }
  
    return count;
}
  
// Driver code
int main()
{
    int L = 10, R = 50;
  
    cout << findCount(L, R);
  
    return 0;
}

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Java

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//Java implementation of the approach
  
import java.io.*;
  
class GFG {
      
// Boolean function to check
// distinct digits of a number
static boolean checkDistinct(int x)
{
    // Take last digit
    int last = x % 10;
  
    // Check if all other digits
    // are same as last digit
    while (x >0) {
        if (x % 10 != last)
            return false;
  
        // Remove last digit
        x = x / 10;
    }
  
    return true;
}
  
// Function to return the count of integers that
// are composed of a single distinct digit only
static int findCount(int L, int R)
{
    int count = 0;
  
    for (int i = L; i <= R; i++) {
  
        // If i has single distinct digit
        if (checkDistinct(i))
            count += 1;
    }
  
    return count;
}
  
// Driver code
    public static void main (String[] args) {
  
          
        int L = 10, R = 50;
        System.out.println (findCount(L, R));
    }
//This code is contributed by ajit.    
}

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Python3

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# Python3 implementation of above approach
  
# Boolean function to check 
# distinct digits of a number 
def checkDistinct(x): 
  
    # Take last digit 
    last = x % 10
  
    # Check if all other digits 
    # are same as last digit 
    while (x):
          
        if (x % 10 != last):
            return False
  
        # Remove last digit 
        x = x // 10
  
    return True
  
# Function to return the count of 
# integers that are composed of a 
# single distinct digit only 
def findCount(L, R):
  
    count = 0
  
    for i in range(L, R + 1): 
  
        # If i has single distinct digit 
        if (checkDistinct(i)):
            count += 1
  
    return count
  
# Driver code 
L = 10
R = 50
  
print(findCount(L, R)) 
  
# This code is contributed
# by saurabh_shukla

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C#

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// C# implementation of the approach
 using System;
   
class GFG {
       
// Boolean function to check
// distinct digits of a number
static Boolean checkDistinct(int x)
{
    // Take last digit
    int last = x % 10;
   
    // Check if all other digits
    // are same as last digit
    while (x >0) {
        if (x % 10 != last)
            return false;
   
        // Remove last digit
        x = x / 10;
    }
   
    return true;
}
   
// Function to return the count of integers that
// are composed of a single distinct digit only
static int findCount(int L, int R)
{
    int count = 0;
   
    for (int i = L; i <= R; i++) {
   
        // If i has single distinct digit
        if (checkDistinct(i))
            count += 1;
    }
   
    return count;
}
   
// Driver code
    static public void Main (String []args) {
   
           
        int L = 10, R = 50;
        Console.WriteLine (findCount(L, R));
    }    
}
//This code is contributed by Arnab Kundu.

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PHP

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<?php
// PHP implementation of the approach 
  
// Boolean function to check distinct
// digits of a number 
function checkDistinct($x
{
    // Take last digit 
    $last = $x % 10; 
  
    // Check if all other digits 
    // are same as last digit 
    while ($x
    
        if ($x % 10 != $last
            return false; 
  
        // Remove last digit 
        $x = floor($x / 10); 
    
  
    return true; 
  
// Function to return the count of integers that 
// are composed of a single distinct digit only 
function findCount($L, $R
    $count = 0; 
  
    for ($i = $L; $i <= $R; $i++) 
    
  
        // If i has single distinct digit 
        if (checkDistinct($i)) 
            $count += 1; 
    
  
    return $count
  
// Driver code 
$L = 10;
$R = 50; 
  
echo findCount($L, $R);
  
// This code is contributed by Ryuga
?>

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