Convert to number with digits as 3 and 8 only

A charming number is a number which only consist 3 and 8 as its digits. We are given a n-digit number you have total of three operations: 
 

1. Adding 1 to given number.
2. Subtracting 1 to given number.
3. Selecting a digit of number and replacing it with any other desired digit.

We need to find the total number of operations to change given number to charming number.
Examples: 
 

Input : num = 343
Output : Minimum Operation = 1

Input : num = 88
Output : Minimum operation = 0

Before moving to proper solution let's have closer look on given operations. 

1. Adding 1 to given number, it will count 1 operation and what it can do is increment last digit by 1 unless it is 9 and if last digit is 9 then it will also change the digits preceding last one. So in the best case if last digit is 2 or 7 this operation will change them to 3 or 8 on the cost of 1 operation.
2. Subtracting 1 to given number, will also count 1 as operation and only decrease the last digit unless it is 0. So in the best case if last digit is 4 or 9 this operation will change them to 3 or 8 on the cost of 1 operation.
3. Selecting any digit and changing its value will count as a single operation but for sure it will change digit to charming digit i.e. 3 or 8. So, in the best as well as worst case this operation will change a single digit at once.

So, for finding the minimum operation addition and subtraction is not going to be useful for us and only the number of digits which are not equal to 3 or 8 are going to be selected and changed. So, total number of digit not equal to 3 or 8 will be our answer.
 

// CPP to find min operations required to
// convert into charming number
#include <bits/stdc++.h>
using namespace std;

// function for minimum operation
int minOp(long long int num)
{
    // remainder and operations count
    int rem;
    int count = 0;

    // count digits not equal to 3 or 8
    while (num) {
        rem = num % 10;
        if (!(rem == 3 || rem == 8))
            count++;
        num /= 10;
    }
    return count;
}

// driver function
int main()
{
    long long int num = 234198;
    cout << "Minimum Operations =" << minOp(num);
    return 0;
}

// Java to find min operations required to
// convert into charming number
public class GFG
{
    
    // function for minimum operation
    static int minOp(int num)
    {
        
        // remainder and operations count
        int rem;
        int count = 0;
    
        // count digits not equal to 3 or 8
        while (num>0) {
            rem = num % 10;
            if (!(rem == 3 || rem == 8))
                count++;
            num /= 10;
        }
        
        return count;
    }
    
    // Driver code
    public static void main (String[] args)
    {
        int num = 234198;
        
        System.out.print("Minimum Operations ="+minOp(num));
    }
}

// This code is contributed by Anant Agarwal.

# Python to find min
# operations required to
# convert into charming number

# function for minimum operation
def minOp(num):

    # remainder and operations count
    count = 0
 
    #count digits not equal to 3 or 8
    while (num):
        rem = num % 10
        if (not(rem == 3 or rem == 8)):
            count=count + 1
        num = num // 10
    
    return count

# Driver code

num = 234198
print("Minimum Operations =" ,minOp(num))

# This code is contributed
# by Anant Agarwal.

// C# to find min operations required to
// convert into charming number
using System;

class GFG
{
    
    // function for minimum operation
    static int minOp(int num)
    {
        
        // remainder and operations count
        int rem;
        int count = 0;
    
        // count digits not equal to 3 or 8
        while (num > 0) 
        {
            rem = num % 10;
            if (! (rem == 3 || rem == 8))
                count++;
            num /= 10;
        }
        
        return count;
    }
    
    // Driver code
    public static void Main ()
    {
        int num = 234198;
    
        Console.WriteLine("Minimum Operations =" + 
                           minOp(num));
    }
}

// This code is contributed by vt_m.

<?php
// PHP to find min operations required to
// convert into charming number

// function for minimum operation
function minOp($num)
{
    
    // remainder and operations count
    $count = 0;

    // count digits not equal to 3 or 8
    while ($num) 
    {
        $rem = intval($num % 10);
        if (!($rem == 3 || $rem == 8))
            $count++;
        $num = intval($num / 10);
    }
    return $count;
}
    
    // Driver Code
    $num = 234198;
    echo "Minimum Operations = " . minOp($num);
    
// This code is contributed by Sam007
?>

<script>


// Javascript to find min operations required to
// convert into charming number

// function for minimum operation
function minOp(num)
{
    // remainder and operations count
    var rem;
    var count = 0;

    // count digits not equal to 3 or 8
    while (num) {
        rem = num % 10;
        if (!(rem == 3 || rem == 8))
            count++;
        num = parseInt(num/10);
    }
    return count;
}

// driver function
var num = 234198;
document.write( "Minimum Operations = " + minOp(num));

</script>    

Minimum Operations =4