Add elements of given arrays with given constraints

Given two integer arrays, add their elements into third array by satisfying following constraints – 

1. Addition should be done starting from 0th index of both arrays. 
2. Split the sum if it is a not a single digit number and store the digits in adjacent locations in output array. 
3. Output array should accommodate any remaining digits of larger input array.

Examples:

Input: 
a = [9, 2, 3, 7, 9, 6]
b = [3, 1, 4, 7, 8, 7, 6, 9]
Output: 
[1, 2, 3, 7, 1, 4, 1, 7, 1, 3, 6, 9]

Input:     
a = [9343, 2, 3, 7, 9, 6]
b = [34, 11, 4, 7, 8, 7, 6, 99]
Output: 
[9, 3, 7, 7, 1, 3, 7, 1, 4, 1, 7, 1, 3, 6, 9, 9]

Input:     
a = []
b = [11, 2, 3 ]
Output: 
[1, 1, 2, 3 ]

Input: 
a = [9, 8, 7, 6, 5, 4, 3, 2, 1]
b = [1, 2, 3, 4, 5, 6, 7, 8, 9]
Output: 
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0]

Difficulty Level: Rookie

The idea is very simple. We maintain an output array and run a loop from the 0th index of both arrays. For each iteration of loop, we consider next elements in both arrays and add them. If the sum is greater than 9, we push the individual digits of the sum to output array else we push the sum itself. Finally we push the remaining elements of larger input array to output array.

Below is the implementation of above idea: 

C++

// C++ program to add two arrays following given
// constraints
#include<bits/stdc++.h>
using namespace std;

// Function to push individual digits of a number
// to output vector from left to right
void split(int num, vector<int> &out)
{
    vector<int> arr;
    while (num)
    {
        arr.push_back(num%10);
        num = num/10;
    }
    // reverse the vector arr and append it to output vector
    out.insert(out.end(), arr.rbegin(), arr.rend());
}

// Function to add two arrays keeping given
// constraints
void addArrays(int arr1[], int arr2[], int m, int n)
{
    // create a vector to store output
    vector<int> out;

    // maintain a variable to store current index in
    // both arrays
    int i = 0;

    // loop till arr1 or arr2 runs out
    while (i < m && i < n)
    {
        // read next elements from both arrays and
        // add them
        int sum = arr1[i] + arr2[i];

        // if sum is single digit number
        if (sum < 10)
            out.push_back(sum);

        else
        {
            // if sum is not a single digit number, push
            // individual digits to output vector
            split(sum, out);
        }

        // increment to next index
        i++;
    }

    // push remaining elements of first input array
    // (if any) to output vector
    while (i < m)
        split(arr1[i++], out);

    // push remaining elements of second input array
    // (if any) to output vector
    while (i < n)
        split(arr2[i++], out);

    // print the output vector
    for (int x : out)
        cout << x << " ";
}

// Driver code
int main()
{
    int arr1[] = {9343, 2, 3, 7, 9, 6};
    int arr2[] = {34, 11, 4, 7, 8, 7, 6, 99};

    int m = sizeof(arr1) / sizeof(arr1[0]);
    int n = sizeof(arr2) / sizeof(arr2[0]);

    addArrays(arr1, arr2, m, n);

    return 0;
}

Java

// Java program to add two arrays following given
// constraints
import java.util.Vector;

class GFG
{

    // Function to push individual digits of a number
    // to output vector from left to right
    static void split(int num, Vector<Integer> out)
    {
        Vector<Integer> arr = new Vector<>();
        while (num > 0)
        {
            arr.add(num % 10);
            num /= 10;
        }

        // reverse the vector arr and
        // append it to output vector
        for (int i = arr.size() - 1; i >= 0; i--)
            out.add(arr.elementAt(i));
    }

    // Function to add two arrays keeping given
    // constraints
    static void addArrays(int[] arr1, int[] arr2,
                          int m, int n)
    {

        // create a vector to store output
        Vector<Integer> out = new Vector<>();

        // maintain a variable to store
        //  current index in both arrays
        int i = 0;

        // loop till arr1 or arr2 runs out
        while (i < m && i < n)
        {

            // read next elements from both arrays
            // and add them
            int sum = arr1[i] + arr2[i];

            // if sum is single digit number
            if (sum < 10)
                out.add(sum);
            else

                // if sum is not a single digit number,
                // push individual digits to output vector
                split(sum, out);

            // increment to next index
            i++;
        }

        // push remaining elements of first input array
        // (if any) to output vector
        while (i < m)
            split(arr1[i++], out);

        // push remaining elements of second input array
        // (if any) to output vector
        while (i < n)
            split(arr2[i++], out);

        // print the output vector
        for (int x : out)
            System.out.print(x + " ");
    }

    // Driver Code
    public static void main(String[] args)
    {
        int[] arr1 = { 9343, 2, 3, 7, 9, 6 };
        int[] arr2 = { 34, 11, 4, 7, 8, 7, 6, 99 };

        int m = arr1.length;
        int n = arr2.length;

        addArrays(arr1, arr2, m, n);
    }
}

// This code is contributed by
// sanjeev2552

Python3

# Python program to add two arrays
# following given constraints

# Function to push individual digits
# of a number to output list from
# left to right
def split(num, out):
    arr = []
    while num:
        arr.append(num % 10)
        num = num // 10

    for i in range(len(arr) - 1, -1, -1):
        out.append(arr[i])

# Function to add two arrays keeping given
# constraints
def add_arrays(arr1, arr2, m, n):
    # Create a list to store output
    out = []

    # Maintain a variable to store
    # current index in both arrays
    i = 0

    # Loop till arr1 or arr2 runs out
    while i < m and i < n:
        # Read next elements from both
        # arrays and add them
        sum = arr1[i] + arr2[i]

        # If sum is single digit number
        if sum < 10:
            out.append(sum)
        else:
            # If sum is not a single digit
            # number, push individual digits
            # to output list
            split(sum, out)
        # Increment to next index
        i += 1

    # Push remaining elements of first
    # input array (if any) to output list
    while i < m:
        split(arr1[i], out)
        i += 1

    # Push remaining elements of second
    # input array (if any) to output list
    while i < n:
        split(arr2[i], out)
        i += 1

    # Print the output list
    for x in out:
        print(x, end = " ")

# Driver code
arr1 = [9343, 2, 3, 7, 9, 6]
arr2 = [34, 11, 4, 7, 8, 7, 6, 99]

m = len(arr1)
n = len(arr2)

add_arrays(arr1, arr2, m, n)

# This code is contributed by akashish__

C#

// C# program to add two arrays following given
// constraints
using System;
using System.Collections.Generic;

class GFG
{

    // Function to push individual digits of a number
    // to output vector from left to right
    static void split(int num, List<int> outs)
    {
        List<int> arr = new List<int>();
        while (num > 0)
        {
            arr.Add(num % 10);
            num /= 10;
        }

        // reverse the vector arr and
        // append it to output vector
        for (int i = arr.Count - 1; i >= 0; i--)
            outs.Add(arr[i]);
    }

    // Function to add two arrays keeping given
    // constraints
    static void addArrays(int[] arr1, int[] arr2,
                        int m, int n)
    {

        // create a vector to store output
        List<int> outs = new List<int>();

        // maintain a variable to store
        // current index in both arrays
        int i = 0;

        // loop till arr1 or arr2 runs out
        while (i < m && i < n)
        {

            // read next elements from both arrays
            // and add them
            int sum = arr1[i] + arr2[i];

            // if sum is single digit number
            if (sum < 10)
                outs.Add(sum);
            else

                // if sum is not a single digit number,
                // push individual digits to output vector
                split(sum, outs);

            // increment to next index
            i++;
        }

        // push remaining elements of first input array
        // (if any) to output vector
        while (i < m)
            split(arr1[i++], outs);

        // push remaining elements of second input array
        // (if any) to output vector
        while (i < n)
            split(arr2[i++], outs);

        // print the output vector
        foreach (int x in outs)
            Console.Write(x + " ");
    }

    // Driver Code
    public static void Main(String[] args)
    {
        int[] arr1 = { 9343, 2, 3, 7, 9, 6 };
        int[] arr2 = { 34, 11, 4, 7, 8, 7, 6, 99 };

        int m = arr1.Length;
        int n = arr2.Length;

        addArrays(arr1, arr2, m, n);
    }
}

// This code is contributed by PrinciRaj1992

Javascript

<script>

// Javascript program to add two arrays
// following given constraints

// Function to push individual digits
// of a number to output vector from
// left to right
function split(num, out)
{
    let arr = [];
    while (num)
    {
        arr.push(num % 10);
        num = Math.floor(num / 10);
    }

    for(let i = arr.length - 1; i >= 0; i--)
        out.push(arr[i]);
}

// Function to add two arrays keeping given
// constraints
function addArrays(arr1, arr2, m, n)
{

    // Create a vector to store output
    let out = [];

    // Maintain a variable to store
    // current index in both arrays
    let i = 0;

    // Loop till arr1 or arr2 runs out
    while (i < m && i < n)
    {

        // Read next elements from both
        // arrays and add them
        let sum = arr1[i] + arr2[i];

        // If sum is single digit number
        if (sum < 10)
            out.push(sum);

        else
        {

            // If sum is not a single digit
            // number, push individual digits
            // to output vector
            split(sum, out);
        }

        // Increment to next index
        i++;
    }

    // Push remaining elements of first
    // input array (if any) to output vector
    while (i < m)
        split(arr1[i++], out);

    // Push remaining elements of second
    // input array (if any) to output vector
    while (i < n)
        split(arr2[i++], out);

    // Print the output vector
    for(let x of out)
        document.write(x + " ");
}

// Driver code
let arr1 = [ 9343, 2, 3, 7, 9, 6 ];
let arr2 = [ 34, 11, 4, 7, 8, 7, 6, 99 ];

let m = arr1.length;
let n = arr2.length;

addArrays(arr1, arr2, m, n);

// This code is contributed by _saurabh_jaiswal

</script>

Output

9 3 7 7 1 3 7 1 4 1 7 1 3 6 9 9 

Time complexity of above solution is O(m + n) as we traverses both arrays exactly once.

Method 2(using String and STL):

in this approach we will take one string named “ans”. as we add the element of both arrays the resultant sum will be converted to string and this string will be appended with main string “ans”.

After doing this for all elements we will take one vector and transfer the whole string to that vector and finally will print that vector.

Below is implementation of above approach:

C++

// C++ program to add two arrays
// following given constrains
#include <bits/stdc++.h>
using namespace std;
// function to add two arrays
// following given constrains
void creat_new(int arr1[], int arr2[], int n, int m)
{

    string ans;
    int i = 0;
    while (i < min(n, m)) {
        // adding the elements
        int sum = arr1[i] + arr2[i];
        // converting the integer to string
        string s = to_string(sum);
        // appending the string
        ans += s;
        i++;
    }
    // entering remaining element(if any) of
    // first array
    for (int j = i; j < n; j++) {
        string s = to_string(arr1[j]);
        ans += s;
    }
    // entering remaining element (if any) of
    // second array
    for (int j = i; j < m; j++) {
        string s = to_string(arr2[j]);
        ans += s;
    }

    // taking vector
    vector<int> k;
    // assigning the elements of string
    // to vector
    for (int i = 0; i < ans.length(); i++) {
        k.push_back(ans[i] - '0');
    }
    // printing the elements of vector
    for (int i = 0; i < k.size(); i++) {
        cout << k[i] << " ";
    }
}
// driver code
int main()
{
    int arr1[] = { 9, 2, 3, 7, 9, 6 };
    int arr2[] = { 3, 1, 4, 7, 8, 7, 6, 9 };
    int n = sizeof(arr1) / sizeof(arr1[0]);
    int m = sizeof(arr2) / sizeof(arr2[0]);
    // function call
    creat_new(arr1, arr2, n, m);
    return 0;
}

// this code is contributed by Machhaliya Muhammad

Java

/*package whatever //do not write package name here */
import java.util.*;
class GFG {

  // function to add two arrays
  // following given constrains
  static void creat_new(int arr1[], int arr2[], int n,
                        int m)
  {

    String ans = "";
    int i = 0;
    while (i < Math.min(n, m))
    {

      // adding the elements
      int sum = arr1[i] + arr2[i];

      // converting the integer to string
      String s = sum + "";
      // appending the string
      ans += s;
      i++;
    }

    // entering remaining element(if any) of
    // first array
    for (int j = i; j < n; j++) {
      String s = arr1[j] + "";
      ans += s;
    }

    // entering remaining element (if any) of
    // second array
    for (int j = i; j < m; j++) {
      String s = arr2[j] + "";
      ans += s;
    }

    // taking vector
    ArrayList<Integer> k = new ArrayList<>();

    // assigning the elements of string
    // to vector
    for (int j = 0; j < ans.length(); j++) {
      k.add(ans.charAt(j) - '0');
    }

    // printing the elements of vector
    for (int j = 0; j < k.size(); j++) {
      System.out.print(k.get(j) + " ");
    }
  }
  public static void main(String[] args)
  {
    int arr1[] = { 9, 2, 3, 7, 9, 6 };
    int arr2[] = { 3, 1, 4, 7, 8, 7, 6, 9 };
    int n = arr1.length;
    int m = arr2.length;

    // function call
    creat_new(arr1, arr2, n, m);
  }
}

// This code is contributed by aadityaburujwale.

Python3

import math
class GFG :

    # function to add two arrays
    # following given constrains
    @staticmethod
    def creat_new( arr1,  arr2,  n,  m) :
        ans = ""
        i = 0
        while (i < min(n,m)) :

            # adding the elements
            sum = arr1[i] + arr2[i]

            # converting the integer to string
            s = str(sum) + ""

            # appending the string
            ans += s
            i += 1

        # entering remaining element(if any) of
        # first array
        j = i
        while (j < n) :
            s = str(arr1[j]) + ""
            ans += s
            j += 1

        # entering remaining element (if any) of
        # second array
        j = i
        while (j < m) :
            s = str(arr2[j]) + ""
            ans += s
            j += 1

        # taking vector
        k =  []

        # assigning the elements of string
        # to vector
        j = 0
        while (j < len(ans)) :
            k.append(ord(ans[j]) - ord('0'))
            j += 1

        # printing the elements of vector
        j = 0
        while (j < len(k)) :
            print(k[j],end=' ')
            j += 1
    @staticmethod
    def main( args) :
        arr1 = [9, 2, 3, 7, 9, 6]
        arr2 = [3, 1, 4, 7, 8, 7, 6, 9]
        n = len(arr1)
        m = len(arr2)

        # function call
        GFG.creat_new(arr1, arr2, n, m)

if __name__=="__main__":
    GFG.main([])

    # This code is contributed by aadityaburujwale.

C#

// Include namespace system
using System;
using System.Collections.Generic;

public class GFG
{

  // function to add two arrays
  // following given constrains
  public static void creat_new(int[] arr1, int[] arr2, int n, int m)
  {
    var ans = "";
    var i = 0;
    while (i < Math.Min(n,m))
    {

      // adding the elements
      var sum = arr1[i] + arr2[i];

      // converting the integer to string
      var s = sum.ToString() + "";

      // appending the string
      ans += s;
      i++;
    }

    // entering remaining element(if any) of
    // first array
    for (int j = i; j < n; j++)
    {
      var s = arr1[j].ToString() + "";
      ans += s;
    }

    // entering remaining element (if any) of
    // second array
    for (int j = i; j < m; j++)
    {
      var s = arr2[j].ToString() + "";
      ans += s;
    }

    // taking vector
    var k = new List<int>();

    // assigning the elements of string
    // to vector
    for (int j = 0; j < ans.Length; j++)
    {
      k.Add((int)(ans[j]) - (int)('0'));
    }

    // printing the elements of vector
    for (int j = 0; j < k.Count; j++)
    {
      Console.Write(k[j] + " ");
    }
  }
  public static void Main(String[] args)
  {
    int[] arr1 = {9, 2, 3, 7, 9, 6};
    int[] arr2 = {3, 1, 4, 7, 8, 7, 6, 9};
    var n = arr1.Length;
    var m = arr2.Length;

    // function call
    GFG.creat_new(arr1, arr2, n, m);
  }
}

// This code is contributed by aadityaburujwale.

Javascript

// JavaScript Code

// function to add two arrays
// following given constrains
const creat_new = (arr1, arr2, n, m) => {
    let ans = "";
    let i = 0;
    while (i < Math.min(n, m))
    {

        // adding the elements
        let sum = arr1[i] + arr2[i];

        // converting the integer to string
        let s = sum.toString();

        // appending the string
        ans += s;
        i++;
    }

    // entering remaining element(if any) of
    // first array
    for (let j = i; j < n; j++) {
        let s = arr1[j].toString();
        ans += s;
    }

    // entering remaining element (if any) of
    // second array
    for (let j = i; j < m; j++) {
        let s = arr2[j].toString();
        ans += s;
    }

    // taking vector
    let k = [];

    // assigning the elements of string
    // to vector
    for (let i = 0; i < ans.length; i++) {
        k.push(parseInt(ans[i]));
    }

    // printing the elements of vector
    console.log(k);
}

// Driver code
let arr1 = [9, 2, 3, 7, 9, 6];
let arr2 = [3, 1, 4, 7, 8, 7, 6, 9];
let n = arr1.length;
let m = arr2.length;

// function call
creat_new(arr1, arr2, n, m);

// This code is contributed by akashish__

Output

1 2 3 7 1 4 1 7 1 3 6 9 

Time Complexity: O(max(m,n))

Auxiliary Space:O(m+n), since vector k(of size m+n in worst case) is being created.

This article is contributed by Aditya Goel. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.