Last Updated: 27 Feb, 2021

Merge Two Sorted Arrays

Moderate

Asked in companies

Solve now

Problem statement

Ninja has been given two sorted integer arrays/lists ‘ARR1’ and ‘ARR2’ of size ‘M’ and ‘N’. Ninja has to merge these sorted arrays/lists into ‘ARR1’ as one sorted array. You may have to assume that ‘ARR1’ has a size equal to ‘M’ + ‘N’ such that ‘ARR1’ has enough space to add all the elements of ‘ARR2’ in ‘ARR1’.

For example:

‘ARR1’ = [3 6 9 0 0]
‘ARR2’ = [4 10]
After merging the ‘ARR1’ and ‘ARR2’ in ‘ARR1’. 
‘ARR1’ = [3 4 6 9 10]

Input Format

The first line of input contains an integer ‘T’ which denotes the number of test cases or queries to be run. Then the test cases follow.

The first line of each test case contains two space-separated integers ‘M’ and ‘N’, which represent the size of ‘ARR1’ and ‘ARR2’.

The next lines of each test case contain ‘M’ space-separated integers and ‘N’ zeros (i.e. 0) which represent the number of elements in ‘ARR1’.

The next lines of each test case contain ‘N’ space-separated integers which represent the number of elements in ‘ARR2’.

Output Format :

For each test case, return the ‘ARR1’ after merging.

Print the output of each test case in a separate line.

Note:

You do not need to print anything; it has already been taken care of. Just implement the given function.

Constraints:

1 <= ‘T’ <= 100
1 <= ‘M’, ‘N’ <= 5000
1 <= ‘ARR1[i], ARR2[i]’ <= 100000

Time Limit: 1 second

Solve now

Approaches

01 Approach

Our main task is that after merging ‘ARR2’ into ‘ARR1’. The resultant ‘ARR1’ is also sorted. So first we simply add all the elements of ‘ARR2’ into ‘ARR1’. Then we can apply any sorting algorithm to sort ‘ARR1’.

Algorithm:

We run a loop for ‘i’ = 0 to ‘N’:
- ‘ARR1[M + i]’ = ‘ARR2[i]’
Sort the array/list ‘ARR1’.
Finally, return ‘ARR1’.

Solve now

02 Approach

As we know both ‘ARR1’ and ‘ARR2’ are sorted. So we can declare two variables ‘i’ and ‘j’ and initialize ‘i’ with ‘M’ and ‘j’ with ‘N’. Then we compare the last element of both arrays/lists and we insert the larger element to the end of the ‘ARR1’. We continue this process while all the elements of ‘ARR2’ are not merged into ‘ARR1’.

Algorithm:

We declare two variables ‘i’ and ‘j’ and initialize ‘i’ with ‘M’ and ‘j’ with ‘N’.
We declare a variable ‘LAST_INDEX’ and initialize it with ‘M+N’.
We run a loop while ‘j’ >= 0:
- If ‘i’ >= 0 and ‘ARR1[i]’ > ‘ARR2[j]’:
  - ‘ARR1[LAST_INDEX] = ‘ARR1[i]’
  - ‘i’--
- Else:
  - ‘ARR1[LAST_INDEX] = ‘ARR2[j]’
  - ‘j’--
- ‘LAST_INDEX’--
Finally, Return ‘ARR1’.

Solve now