Count of alphabets whose ASCII values can be formed with the digits of N

Given an integer N. You can select any two digits from this number (the digits can be same but their positions should be different) and order them in any one of the two possible ways. For each of these ways, you create a two digit number from it (might contain leading zeros). Then, you will pick a character corresponding to the ASCII value equal to this number, i.e. the number 65 corresponds to ‘A’, 66 to ‘B’ and so on. The task is to count the number of english alphabets (lowercase or uppercase) that can be picked in this way.
Examples:

Input: N = 656 
Output: 2 
Only the characters ‘A’ (65) and ‘B’ (66) are possible.
Input: N = 1623455078 
Output: 27 

Approach: The idea is to observe that the total number of possible characters are (26 lowercase + 26 uppercase = 52). So, instead of generating all possible combinations of two digits from N, check the occurrences of these 52 characters. 
Therefore, count the occurrences of each digit in N then for every character (lowercase or uppercase), find its ASCII value and check whether it can be picked from the given digits. Print the count of such alphabets in the end.
Below is the implementation of the above approach: 

C++

// C++ implementation of the approach
#include<bits/stdc++.h>

using namespace std;

// Function that returns true if num
// can be formed with the digits in
// digits[] array
bool canBePicked(int digits[], int num)
{

    int copyDigits[10];

    // Copy of the digits array
    for(int i =0 ; i < 10;i++)
        copyDigits[i]=digits[i];

    while (num > 0)
    {
        // Get last digit
        int digit = num % 10;

        // If digit array doesn't contain
        // current digit
        if (copyDigits[digit] == 0)
            return false;

        // One occurrence is used
        else
            copyDigits[digit] -= 1;

        // Remove the last digit
        num = floor(num / 10);
    }

    return true;
}

// Function to return the count of
// required alphabets
int countAlphabets(long n)
{

    int count = 0;

    // To store the occurrences of
    // digits (0 - 9)
    int digits[10]= {0};
    while (n > 0)
    {

        // Get last digit
        int digit = n % 10;

        // Update the occurrence of the digit
        digits[digit] += 1;

        // Remove the last digit
        n = floor(n / 10);
    }

    // If any lowercase character can be
    // picked from the current digits
    for(int i = 97; i <= 122 ;i ++)
        if (canBePicked(digits, i))
            count += 1;

    // If any uppercase character can be
    // picked from the current digits
    for(int i = 65; i < 91;i++)
        if (canBePicked(digits, i))
            count += 1;

    // Return the required count
    // of alphabets
    return count;
}

// Driver code
int main()
{

    long n = 1623455078;
    cout<<(countAlphabets(n));
}

// This code is contributed by chitranayal

Java

// Java implementation of the approach
import java.io.*;
import java.util.*;
class GFG {

    // Function that returns true if num can be formed
    // with the digits in digits[] array
    static boolean canBePicked(int digits[], int num)
    {
        // Copy of the digits array
        int copyDigits[] = digits.clone();
        while (num > 0) {

            // Get last digit
            int digit = num % 10;

            // If digit array doesn't contain current digit
            if (copyDigits[digit] == 0)
                return false;

            // One occurrence is used
            else
                copyDigits[digit]--;

            // Remove the last digit
            num /= 10;
        }

        return true;
    }

    // Function to return the count of required alphabets
    static int countAlphabets(int n)
    {
        int i, count = 0;

        // To store the occurrences of digits (0 - 9)
        int digits[] = new int[10];
        while (n > 0) {

            // Get last digit
            int digit = n % 10;

            // Update the occurrence of the digit
            digits[digit]++;

            // Remove the last digit
            n /= 10;
        }

        // If any lowercase character can be picked
        // from the current digits
        for (i = 'a'; i <= 'z'; i++)
            if (canBePicked(digits, i))
                count++;

        // If any uppercase character can be picked
        // from the current digits
        for (i = 'A'; i <= 'Z'; i++)
            if (canBePicked(digits, i))
                count++;

        // Return the required count of alphabets
        return count;
    }

    // Driver code
    public static void main(String[] args)
    {
        int n = 1623455078;
        System.out.println(countAlphabets(n));
    }
}

Python3

# Python3 implementation of the approach
import math

# Function that returns true if num
# can be formed with the digits in
# digits[] array
def canBePicked(digits, num):

    copyDigits = [];

    # Copy of the digits array
    for i in range(len(digits)):
        copyDigits.append(digits[i]);

    while (num > 0):

        # Get last digit
        digit = num % 10;

        # If digit array doesn't contain
        # current digit
        if (copyDigits[digit] == 0):
            return False;

        # One occurrence is used
        else:
            copyDigits[digit] -= 1;

        # Remove the last digit
        num = math.floor(num / 10);

    return True;

# Function to return the count of
# required alphabets
def countAlphabets(n):

    count = 0;

    # To store the occurrences of
    # digits (0 - 9)
    digits = [0] * 10;
    while (n > 0):

        # Get last digit
        digit = n % 10;

        # Update the occurrence of the digit
        digits[digit] += 1;

        # Remove the last digit
        n = math.floor(n / 10);

    # If any lowercase character can be
    # picked from the current digits
    for i in range(ord('a'), ord('z') + 1):
        if (canBePicked(digits, i)):
            count += 1;

    # If any uppercase character can be
    # picked from the current digits
    for i in range(ord('A'), ord('Z') + 1):
        if (canBePicked(digits, i)):
            count += 1;

    # Return the required count
    # of alphabets
    return count;

# Driver code
n = 1623455078;
print(countAlphabets(n));

# This code is contributed by mits

C#

// C# implementation of the approach
using System;

class GFG
{

    // Function that returns true
    // if num can be formed with
    // the digits in digits[] array
    static bool canBePicked(int []digits, int num)
    {
        // Copy of the digits array
        int []copyDigits = (int[]) digits.Clone();
        while (num > 0)
        {

            // Get last digit
            int digit = num % 10;

            // If digit array doesn't
            // contain current digit
            if (copyDigits[digit] == 0)
                return false;

            // One occurrence is used
            else
                copyDigits[digit]--;

            // Remove the last digit
            num /= 10;
        }

        return true;
    }

    // Function to return the count
    // of required alphabets
    static int countAlphabets(int n)
    {
        int i, count = 0;

        // To store the occurrences
        // of digits (0 - 9)
        int[] digits = new int[10];
        while (n > 0)
        {

            // Get last digit
            int digit = n % 10;

            // Update the occurrence of the digit
            digits[digit]++;

            // Remove the last digit
            n /= 10;
        }

        // If any lowercase character can be
        // picked from the current digits
        for (i = 'a'; i <= 'z'; i++)
            if (canBePicked(digits, i))
                count++;

        // If any uppercase character can be
        // picked from the current digits
        for (i = 'A'; i <= 'Z'; i++)
            if (canBePicked(digits, i))
                count++;

        // Return the required count of alphabets
        return count;
    }

    // Driver code
    public static void Main()
    {
        int n = 1623455078;
        Console.WriteLine(countAlphabets(n));
    }
}

// This code is contributed by
// tufan_gupta2000

PHP

<?php
// PHP implementation of the approach

// Function that returns true if num
// can be formed with the digits in
// digits[] array
function canBePicked($digits, $num)
{
    $copyDigits = array();

    // Copy of the digits array
    for($i = 0; $i < sizeof($digits); $i++)
        $copyDigits[$i] = $digits[$i];

    while ($num > 0)
    {

        // Get last digit
        $digit = $num % 10;

        // If digit array doesn't contain
        // current digit
        if ($copyDigits[$digit] == 0)
            return false;

        // One occurrence is used
        else
            $copyDigits[$digit]--;

        // Remove the last digit
        $num = floor($num / 10);
    }

    return true;
}

// Function to return the count of
// required alphabets
function countAlphabets($n)
{
    $count = 0;

    // To store the occurrences of
    // digits (0 - 9)
    $digits = array_fill(0, 10, 0);
    while ($n > 0)
    {

        // Get last digit
        $digit = $n % 10;

        // Update the occurrence of the digit
        $digits[$digit]++;

        // Remove the last digit
        $n = floor($n / 10);
    }

    // If any lowercase character can be
    // picked from the current digits
    for ($i = ord('a'); $i <= ord('z'); $i++)
        if (canBePicked($digits, $i))
            $count++;

    // If any uppercase character can be
    // picked from the current digits
    for ($i = ord('A');
         $i <= ord('Z'); $i++)
        if (canBePicked($digits, $i))
            $count++;

    // Return the required count
    // of alphabets
    return $count;
}

// Driver code
$n = 1623455078;
echo countAlphabets($n);

// This code is contributed by Ryuga
?>

Javascript

<script>
 //Javascript implementation of the approach

// Function that returns true if num
// can be formed with the digits in
// digits[] array
function canBePicked( digits, num)
{

    var copyDigits = new Array(10);;

    // Copy of the digits array
    for(var i =0 ; i < 10;i++)
        copyDigits[i]=digits[i];

    while (num > 0)
    {
        // Get last digit
        var digit = num % 10;

        // If digit array doesn't contain
        // current digit
        if (copyDigits[digit] == 0)
            return false;

        // One occurrence is used
        else
            copyDigits[digit] -= 1;

        // Remove the last digit
        num = Math.floor(num / 10);
    }

    return true;
}

// Function to return the count of
// required alphabets
function countAlphabets( n)
{

    var count = 0;

    // To store the occurrences of
    // digits (0 - 9)
    var digits = new Array(10);
    digits.fill(0);

    while (n > 0)
    {

        // Get last digit
        var digit = n % 10;

        // Update the occurrence of the digit
        digits[digit] += 1;

        // Remove the last digit
        n = Math.floor(n / 10);
    }

    // If any lowercase character can be
    // picked from the current digits
    for(var i = 97; i <= 122 ;i ++)
        if (canBePicked(digits, i))
            count += 1;

    // If any uppercase character can be
    // picked from the current digits
    for(var i = 65; i < 91;i++)
        if (canBePicked(digits, i))
            count += 1;

    // Return the required count
    // of alphabets
    return count;
}

var n = 1623455078;
document.write(countAlphabets(n));

// This code is contributed by SoumikMondal
</script>

Output:

27

 Time Complexity: O(n log n)

Auxiliary Space: O(10)