[LintCode] 两个排序数组的中位数

class Solution {
public:
    /**
     * @param A: An integer array.
     * @param B: An integer array.
     * @return: a double whose format is *.5 or *.0
     */
    double findMedianSortedArrays(vector<int> A, vector<int> B) {
        // write your code here
        int m = A.size(), n = B.size();
        if (m > n) return findMedianSortedArrays(B, A);
        int imin = 0, imax = m, half = (m + n + 1) / 2, i, j, num1, num2;
        while (imin <= imax) {
            i = (imin + imax) / 2;
            j = half - i;
            if (j > 0 && i < m && B[j - 1] > A[i])
                imin = i + 1;
            else if (i > 0 && j < n && A[i - 1] > B[j])
                imax = i - 1;
            else {
                if (!i) num1 = B[j - 1];
                else if (!j) num1 = A[i - 1];
                else num1 = max(A[i - 1], B[j - 1]);
                break;
            }
        }
        if ((m + n) % 2) return num1;
        if (i == m) num2 = B[j];
        else if (j == n) num2 = A[i];
        else num2 = min(A[i], B[j]);
        return (num1 + num2) / 2.0;
    }
};