Median of Two Sorted Arrays

There are two sorted arrays nums1 and nums2 of size m and n respectively.

Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

Example 1:

nums1 = [1, 3]
nums2 = [2]

The median is 2.0

Example 2:

nums1 = [1, 2]
nums2 = [3, 4]

The median is (2 + 3)/2 = 2.5

Tips:

要用二分法 O(log (m+n))

Code：

class Solution {
    /**
     * @param A: An integer array.
     * @param B: An integer array.
     * @return: a double whose format is *.5 or *.0
     */
    public double findMedianSortedArrays(int[] A, int[] B) {
        // write your code here
        int len = A.length + B.length;
        if (len % 2 == 1){
            return findMedian(A, 0, B, 0, len / 2 + 1);
        } else {
            return (findMedian(A, 0, B, 0, len/2) + findMedian(A, 0, B, 0, len / 2 + 1)) / 2.0;
        }
    }
    private static int findMedian(int[] A, int A_start, int[] B, int B_start, int k){
        if (A_start >= A.length){
            return B[B_start + k -1];
        }
        if (B_start >= B.length){
            return A[A_start + k -1];
        }
        if (k == 1){
            return Math.min(A[A_start], B[B_start]);
        }
        int A_key = A_start + k / 2 -1 < A.length ? A[A_start + k / 2 -1] : Integer.MAX_VALUE;
        int B_key = B_start + k / 2 -1 < B.length ? B[B_start + k / 2 -1] : Integer.MAX_VALUE;
        if (A_key < B_key){
            return findMedian(A, A_start + k/2, B, B_start, k - k/2);
        } else {
            return findMedian(A, A_start, B, B_start + k/2, k - k/2);
        }

    }
}