double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
int m = nums1.size(), n = nums2.size();
if ((m+n)%2==0)
return (findKthNumber(nums1, 0, nums2, 0, (m+n)/2)+findKthNumber(nums1, 0, nums2, 0, (m+n)/2+1))/2;
else
return findKthNumber(nums1, 0, nums2, 0, (m+n)/2+1);
}
double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
int size1 = nums1.size(), size2 = nums2.size(), size = size1+ size2;
if (size % 2) return findKthNumber(nums1, 0, nums2, 0, size / 2 + 1);
else return (findKthNumber(nums1, 0, nums2, 0, size / 2) + findKthNumber(nums1, 0, nums2, 0, size / 2 + 1)) / 2.0;
}
int findKthNumber(vector<int> & nums1, int start1, vector<int> & nums2, int start2, int k) {
int size1 = nums1.size(), size2 = nums2.size();
if (size1 - start1 > size2 - start2) return findKthNumber(nums2, start2, nums1, start1, k);
if (size1 - start1 == 0) return nums2[start2 + k - 1];
if (k == 1) return min(nums1[start1], nums2[start2]);
int a = min(k / 2, size1 - start1), b = k - a;
if (nums1[start1 + a - 1] < nums2[start2 + b - 1]) return findKthNumber(nums1, start1 + a, nums2, start2, k - a);
else return findKthNumber(nums1, start1, nums2, start2 + b, k - b);
}
double findKthNumber(vector<int>& nums1, int p1, vector<int>& nums2, int p2, int k) {
int m = nums1.size(), n = nums2.size();
if (m-p1>n-p2) return findKthNumber(nums2, p2, nums1, p1, k);
if (m-p1==0) return nums2[k-1];
if (k==1) return min(nums1[p1], nums2[p2]);
int offset1 = min(k/2, m-p1), offset2 = k-offset1;
int q1 = p1+offset1-1, q2 = p2+offset2-1;
if (nums1[q1]<nums2[q2])
return findKthNumber(nums1, q1+1, nums2, p2, k-offset1);
else
if (nums1[q1]>nums2[q2])
return findKthNumber(nums1, p1, nums2, q2+1, k-offset2);
else
return nums1[q1];
}
