leetcode4 Median of Two Sorted Arrays

思路：

二分，参考了https://www.cnblogs.com/voidsky/p/5373982.html

实现：

 1 class Solution
 2 {
 3 public:
 4     double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2)
 5     {
 6         int n = nums1.size(), m = nums2.size();
 7         if (n > m) return findMedianSortedArrays(nums2, nums1);
 8         int l = 0, r = 2 * n;
 9         long long l1, l2, r1, r2;
10         while (l <= r)
11         {
12             int c1 = l + r >> 1, c2 = m + n - c1;
13             l1 = c1 == 0 ? INT_MIN : nums1[c1 - 1 >> 1];
14             r1 = c1 == 2 * n ? INT_MAX : nums1[c1 >> 1];
15             l2 = c2 == 0 ? INT_MIN : nums2[c2 - 1 >> 1];
16             r2 = c2 == 2 * m ? INT_MAX : nums2[c2 >> 1];
17             if (l1 > r2) r = c1 - 1;
18             else if (l2 > r1) l = c1 + 1;
19             else break;
20         }
21         long long res = max(l1, l2) + min(r1, r2);
22         return (double)res / 2.0;
23     }
24 }