L2：11 - Median of Two Sorted Arrays

https://oj.leetcode.com/problems/median-of-two-sorted-arrays/

There are two sorted arrays A and B 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)).

/**
 * Copyright: NineChapter
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 */

public class Solution {
    public double findMedianSortedArrays(int A[], int B[]) {
        int len = A.length + B.length;
        if (len % 2 == 0) {
            return (findKth(A, 0, B, 0, len / 2) + findKth(A, 0, B, 0, len / 2 + 1)) / 2.0 ;
        } else {
            return findKth(A, 0, B, 0, len / 2 + 1);
        }
    }
    
    // find kth number of two sorted array
    public static int findKth(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 findKth(A, A_start + k / 2, B, B_start, k - k / 2);
		} else {
			return findKth(A, A_start, B, B_start + k / 2, k - k / 2);
		}
	}
}