Leet Code 4 求两个有序数组的中位数 - Java

[code=language-java]public class Solution {
public static double findMedianSortedArrays(int A[], int B[]) {
int m = A.length;
int n = B.length;

if ((m + n) % 2 != 0) {
// 两个数组的元素总个数为奇数
return (double) findKth(A, B, (m + n) / 2, 0, m - 1, 0, n - 1);
} else {
// 两个数组的元素总个数为偶数
return (findKth(A, B, (m + n) / 2, 0, m - 1, 0, n - 1) + findKth(A, B,
(m + n) / 2 - 1, 0, m - 1, 0, n - 1)) * 0.5;
}
}

public static int findKth(int A[], int B[], int k, int aStart, int aEnd,
int bStart, int bEnd) {
int aLen = aEnd - aStart + 1;
int bLen = bEnd - bStart + 1;

if (aLen == 0) {
return B[bStart + k];
}
if (bLen == 0) {
return A[aStart + k];
}
if (k == 0) {
return Math.min(A[aStart], B[bStart]);
}

int aMid = aLen * k / (aLen + bLen);
int bMid = k - aMid - 1;

aMid = aMid + aStart;
bMid = bMid + bStart;

if (A[aMid] > B[bMid]) {
k = k - (bMid - bStart + 1);
aEnd = aMid;
bStart = bMid + 1;
} else {
k = k - (aMid - aStart + 1);
bEnd = bMid;
aStart = aMid + 1;
}

return findKth(A, B, k, aStart, aEnd, bStart, bEnd);
}
}