[LintCode]2つのソート配列の中位数

 1 class Solution {
 2 public:
 3     /**
 4      * @param A: An integer array.
 5      * @param B: An integer array.
 6      * @return: a double whose format is *.5 or *.0
 7      */
 8     double findMedianSortedArrays(vector<int> A, vector<int> B) {
 9         // write your code here
10         int m = A.size(), n = B.size();
11         if (m > n) return findMedianSortedArrays(B, A);
12         int imin = 0, imax = m, half = (m + n + 1) / 2, i, j, num1, num2;
13         while (imin <= imax) {
14             i = (imin + imax) / 2;
15             j = half - i;
16             if (j > 0 && i < m && B[j - 1] > A[i])
17                 imin = i + 1;
18             else if (i > 0 && j < n && A[i - 1] > B[j])
19                 imax = i - 1;
20             else {
21                 if (!i) num1 = B[j - 1];
22                 else if (!j) num1 = A[i - 1];
23                 else num1 = max(A[i - 1], B[j - 1]);
24                 break;
25             }
26         }
27         if ((m + n) % 2) return num1;
28         if (i == m) num2 = B[j];
29         else if (j == n) num2 = A[i];
30         else num2 = min(A[i], B[j]);
31         return (num1 + num2) / 2.0;
32     }
33 };