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# 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``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);``    ``int` `n = ``sizeof``(arr2) / ``sizeof``(arr2);` `    ``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 out)``    ``{``        ``Vector 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 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

 ``

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 ``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);``    ``int` `m = ``sizeof``(arr2) / ``sizeof``(arr2);``    ``// 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 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.