11_decimal_tooctal.cpp

/*
    Take N (number in decimal format). Write a function that converts it to octal format. Print the value returned.

    Constraints: 0 < N <= 1000000000

    Sample Input:    63

    Sample Output:   77
    
    Explanation: Both input and output are integers
*/

#include<iostream>
using namespace std;

int main() {
	int decimal_num;
	cin>>decimal_num;
	 
	int octal_num=0, pow=1;

	while(decimal_num > 0){
		int rem = decimal_num%8;
		octal_num = octal_num + (pow*rem);
		pow = pow * 10;
		decimal_num = decimal_num/8;
	}
	cout<<octal_num<<endl;
	
	return 0;
}

/*
    Algorithm:

    Store the remainder when the number is divided by 8 in an array.
    Divide the number by 8 now
    Repeat the above two steps until the number is not equal to 0.
    Print the array in reverse order now.


    For Example:

    If the given decimal number is 16.
    Step 1: Remainder when 16 is divided by 8 is 0. Therefore, arr[0] = 0.
    Step 2: Divide 16 by 8. New number is 16/8 = 2.
    Step 3: Remainder when 2 is divided by 8 is 2. Therefore, arr[1] = 2.
    Step 4: Divide 2 by 8. New number is 2/8 = 0.
    Step 5: Since number becomes = 0. Stop repeating steps and print the array in reverse order. Therefore the equivalent octal number is 20.
*/