Common elements geeks for geeks in c++

 

Given three arrays sorted in increasing order. Find the elements that are common in all three arrays.

Note: can you take care of the duplicates without using any additional Data Structure?

Example 1:

Input:
n1 = 6; A = {1, 5, 10, 20, 40, 80}
n2 = 5; B = {6, 7, 20, 80, 100}
n3 = 8; C = {3, 4, 15, 20, 30, 70, 80, 120}
Output: 20 80
Explanation: 20 and 80 are the only
common elements in A, B and C.

 

Your Task:  
You don't need to read input or print anything. Your task is to complete the function commonElements() which take the 3 arrays A[], B[], C[] and their respective sizes n1, n2 and n3 as inputs and returns an array containing the common element present in all the 3 arrays in sorted order. 
If there are no such elements return an empty array. In this case the output will be printed as -1.

 

Expected Time Complexity: O(n1 + n2 + n3)
Expected Auxiliary Space: O(n1 + n2 + n3)

 

Constraints:
1 <= n1, n2, n3 <= 10^5
The array elements can be both positive or negative integers.

2. class Solution
3. {
4.     public:    
5.        vector <int> commonElements (int A[], int B[], int C[], int n1, int n2, int n3)
6.         {
7.             //code here.
8.             vector<int> v;
9.             int i=0,j=0,k=0;
10.             while(i<n1 && j<n2 && k<n3)
11.             {
12.                 if(A[i]==B[j]&&A[i]==C[k])
13.                 {
14.                     v.push_back(A[i]);
15.                     i++;
16.                     j++;
17.                     k++;
18.                 }else if(A[i]<B[j])
19.                 {
20.                     i++;
21.                 }else if(B[j]<C[k])
22.                 {
23.                     j++;
24.                 }else 
25.                 {
26.                     k++;
27.                 }
28.             }
29.             sort(v.begin(),v.end());
30.             v.erase(unique(v.begin(),v.end()),v.end());
31.             return v;
32.         }
33. 
    
34. };