Median of Two Sorted Arrays

 1 public class Solution {
 2     public double findMedianSortedArrays(int A[], int B[]) {
 3         int alen = A.length;
 4         int blen = B.length;
 5         if((alen + blen) % 2 == 1) return findKthElement(A, B, 0, alen - 1, 0, blen - 1, (alen + blen + 1) / 2);
 6         else return (double) (findKthElement(A, B, 0, alen - 1, 0, blen - 1, (alen + blen) / 2) + findKthElement(A, B, 0, alen - 1, 0, blen - 1, (alen + blen + 2) / 2)) / 2.0;
 7     }
 8     private int findKthElement(int arra[], int arrb[], int ast, int and, int bst, int bnd, int num){
 9         if(ast > and) return arrb[bst + num - 1];
10         if(bst > bnd) return arra[ast + num - 1];
11         int amid = (ast + and) / 2;
12         int bmid = (bst + bnd) / 2;
13         int len = amid - ast + 1 + bmid - bst + 1;
14         if(arra[amid] < arrb[bmid]){
15             if(len <= num) return findKthElement(arra, arrb, amid + 1, and, bst, bnd, num - amid + ast - 1);
16             else return findKthElement(arra, arrb, ast, and, bst, bmid - 1, num);
17         }else{
18             if(len <= num) return findKthElement(arra, arrb, ast, and, bmid + 1, bnd, num - bmid + bst - 1);
19             else return findKthElement(arra, arrb, ast, amid - 1, bst, bnd, num);
20         }
21     }
22 }