Intersection Of Two Arrays
You are given two arrays 'A' and 'B' of size 'N' and 'M' respectively. Both these arrays are sorted in non-decreasing order. You have to find the intersection of these two arrays.

Intersection of two arrays is an array that consists of all the common elements occurring in both arrays.

Note :

1. The length of each array is greater than zero. 2. Both the arrays are sorted in non-decreasing order. 3. The output should be in the order of elements that occur in the original arrays. 4. If there is no intersection present then return an empty array.

Input Format :

The first line of the input contains an integer 'T', denoting the number of test cases. The first line of each test case contains two integers 'N' 'M', denoting the size of the two arrays. The second line of each test case contains 'N' space-separated integers denoting the elements of the first array. The third line of each test case contains 'M' space-separated integers denoting the elements of the second array.

Output Format :

The only line of output of each test case contains 'K' space-separated integers which correspond to the intersection of the two arrays A and B. The output of each test case will be printed on 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

Question

Intersection Of Two Arrays

You are given two arrays 'A' and 'B' of size 'N' and 'M' respectively. Both these arrays are sorted in non-decreasing order. You have to find the intersection of these two arrays.

Intersection of two arrays is an array that consists of all the common elements occurring in both arrays.

Note :

1. The length of each array is greater than zero.
2. Both the arrays are sorted in non-decreasing order.
3. The output should be in the order of elements that occur in the original arrays.
4. If there is no intersection present then return an empty array.

Input Format :

The first line of the input contains an integer 'T', denoting the number of test cases.

The first line of each test case contains two integers 'N' 'M', denoting the size of the two arrays.

The second line of each test case contains 'N' space-separated integers denoting the elements of the first array.

The third line of each test case contains 'M' space-separated integers denoting the elements of the second array.

Output Format :

The only line of output of each test case contains 'K' space-separated integers which correspond to the intersection of the two arrays A and B.

The output of each test case will be printed on 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 <= N, M <= 10^4
0 <= A[i] <= 10^5
0 <= B[i] <= 10^5

Time Limit: 1 sec

Follow Up:

Can we solve this problem using the time complexity of O(max(N, M)).

Accepted Answer

Union :
1) Initialize an empty hash set or hash map mp;
2) Iterate through the first array and put every element of the first array in the set mp.
3) Repeat the process for the second array.
4) Print the set mp.

Intersection:
1) Initialize an empty set mp.
2) Iterate through the first array and put every element of the first array in the set mp.
3) For every element x of the second array, do the following :
Search x in the set mp. If x is present, then print it.

Time complexity : O(m+n) under the assumption that hash table search and insert operations take O(1) time.
Space complexity : O(m+n) in case of Union and O(min(m,n)) in case of Intersection

Accepted Answer

Hashing

The simplest approach to solve this problem is to use a map to find common elements.
Firstly we can hash all the elements from the first array into a map.
Now we iterate through the second array and check whether the same elements is present in the map or not, if it present then we print it else we continue.
After the end of this loop we will have all the common elements from both the arrays.

Space Complexity: O(n)Explanation:

O(N), where N is the size of the first array.

We are using a map which makes the space complexity O(N)

Time Complexity: OtherExplanation:

O(N+M), where ‘N’ is the size of the first array and ‘M’ is the size of the second array.

We are traversing both arrays. Therefore time complexity is O(N+M)

Accepted Answer

Two Pointer Approach

We can use two pointers to solve this problem. The main idea to use two pointers is that the arrays are sorted.
Let i be the pointer which points at the first array and i = 0.
Let j be the second pointer which points to another array and j = 0.
Now run the loop while i< N and j < M:
- if(arr[i] == brr[j]) then the elements are same so print arr[i] and do j = j + 1 , i = i + 1.
- Else if (arr[i] > brr[j]) then do j = j + 1 because in arr we have already processed some greater element.
- Else do i = i + 1.
After the end of this loop, we will have the common elements from both the arrays.

Space Complexity: O(1)Explanation:

O(1)

We are using constant extra space

Time Complexity: OtherExplanation:

O(max(N, M)), where ‘N’ is the size of the first array and ‘M’ is the size of the second array.

We ar traversing both the arrays simultaneously. Therefore time complexity will be maximum of ‘M’ and ‘N’

You are given two arrays 'A' and 'B' of size 'N' and 'M' respectively. Both these arrays are sorted in non-decreasing order. You have to find the intersection of these two arrays.

Intersection of two arrays is an array that consists of all the common elements occurring in both arrays.

Note :

Input Format :

Output Format :

Note :

Constraints :

Follow Up:

Top BigBasket Software Developer interview questions & answers

Popular interview questions of Software Developer