Divide large number represented as string in Java

In the input, a large number (in the form of a string) is given to us. We need to divide it by another number (in the form of an int data type). Our task is to find the division of these numbers and return the result of those numbers.

Example 1:

Input:

int num = 124587785421

int div = 963

Output:

The result is 129374647

Example 2:

Input:

int num = 12548796324587

int div = 120

Output:

The result is 104573302704

Example 3:

Input:

int num = 475213698410236589560

int div = 33

Output:

The result is 14400415103340502713

Approach: Naïve Approach

Algorithm:

Step 1: Create a StringBuilder in order to save the result.

Step 2: Create a character array from the input string.

Step 3: Set the carry initial value to 0.

Step 4: Carry * 10 + current_digit is the formula to find the current number for each character in the array.

Step 5: As current_number / divisor, compute the partial quotient and add it to the result.

Step 6: Implementing the current_number% divisor, update carry.

Step 7: Find the first non-zero character by iterating over the result.

Step 8: From this character, return the substring to the end.

Step 9: Return "0" in the event that every character in the result is zero.

Step 10: Finally, print the quotient.

Implementation:

FileName: StringLongDivision.java

import java.io.*;
import java.util.*;
public class StringLongDivision 
{
    public static String longDivision(String num, int div) 
    {
        StringBuilder res = new StringBuilder();
        char[] divide = num.toCharArray();
        int carry = 0;
        for (int i = 0; i < divide.length; i++) 
        {
            // Get the number ready to be divided.
            int x = carry * 10 + Character.getNumericValue(divide[i]);
            // Add the partial quotient to the result.
            res.append(x / div);
            // Hold the carry-over to the following iteration.
            carry = x % div;
        }
        // Take off any leading zeros.
        for (int i = 0; i < res.length(); i++) 
        {
            if (res.charAt(i) != '0') 
            {
                // Return the result number
                return res.substring(i);
            }
        }
        // In the case that every digit was zero, return "0".
        return "0";
    }
    public static void main(String[] args) 
    {
        String num = "12548796324587";
        int div = 120;
        System.out.println("The result is: " + longDivision(num, div));
    }
}

Output: