Lintcode: Merge Sorted Array II

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?

没什么好说的，Arraylist来做merge, 建一个新ArrayList

class Solution {
    /**
     * @param A and B: sorted integer array A and B.
     * @return: A new sorted integer array
     */
    public ArrayList<Integer> mergeSortedArray(ArrayList<Integer> A, ArrayList<Integer> B) {
        // write your code here
        if (A==null || A.size()==0) return B;
        if (B==null || B.size()==0) return A;
        ArrayList<Integer> res = new ArrayList<Integer>();
        int i=0, j=0;
        for (int k=0; k<A.size()+B.size(); k++) {
            if (i<A.size() && j<B.size() && A.get(i) < B.get(j)) {
                res.add(A.get(i));
                i++;
            }
            else if (i<A.size() && j<B.size() && A.get(i) >= B.get(j)){
                res.add(B.get(j));
                j++;
            }
            else if (i<A.size()) {
                res.add(A.get(i));
                i++;
            }
            else {
                res.add(B.get(j));
                j++;
            }
        }
        return res;
    }
}