19. Find missing in second array

The problem can be found at the following link: Question Link

My Approach

• We create an unordered set to store all elements of array b.

• Then, we iterate through array a. For each element in a, if it's not present in set b, we push it into the output vector.

• Finally, we return the output vector containing the missing elements.

Time and Auxiliary Space Complexity

• Time Complexity: O(n + m), where n is the size of array a and m is the size of array b.

• Auxiliary Space Complexity: O(m), where m is the size of array b.

Code (C++)

class Solution {
public:
    vector<int> findMissing(int a[], int b[], int n, int m) 
    { 
        unordered_set<int> s;
        vector<int> out;
        for(int i = 0; i < m; ++i) 
            s.insert(b[i]); 
            
        for(int i = 0; i < n; ++i) 
            if(!s.count(a[i])) 
                out.push_back(a[i]);
                
        return out;
    } 
};

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