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;
     }
 }