[Algorithm] 6. Merge Two Sorted Arrays

Description

Merge two given sorted integer array A and B into a new sorted integer array.

Example

A=[1,2,3,4]

B=[2,4,5,6]

return [1,2,2,3,4,4,5,6]

Challenge

How can you optimize your algorithm if one array is very large and the other is very small?

Solution

    /**
     * @param A: sorted integer array A
     * @param B: sorted integer array B
     * @return: A new sorted integer array
     */
    vector<int> mergeSortedArray(vector<int> &A, vector<int> &B) {
        // write your code here
        vector<int> res;
        int maxSize= A.size() > B.size() ? A.size() : B.size();
        int index_a=0,index_b=0;
        
        for(int i=0; i<A.size()+B.size(); i++)
        {
            if(index_b==B.size()){
                for(int i=index_a; i<A.size(); i++)     res.push_back(A[i]);
                return res;
            }
            
            if(index_a==A.size()){
                for(int i=index_b; i<B.size(); i++)     res.push_back(B[i]);
                return res;
            }
            
            if (A[index_a] <= B[index_b]){
                res.push_back(A[index_a]);
                index_a++;
            }else{
                res.push_back(B[index_b]);
                index_b++;
            }
        }
        return res;
    }

 

Tips

Select the minimum element from two arrays in every loop.