[LeetCode]Median of Two Sorted Arrays

There are two sorted arrays A and B of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

參考:http://fisherlei.blogspot.com/2012/12/leetcode-median-of-two-sorted-arrays.html

class Solution {
public:
    double findMedianSortedArrays(int A[], int m, int B[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if((m+n)%2==1)
        {
            return getKth(A,0,m,B,0,n,(m+n)/2+1);
        }
        else
        {
            double med1=getKth(A,0,m,B,0,n,(m+n)/2);
            double med2=getKth(A,0,m,B,0,n,(m+n)/2+1);
            return (med1+med2)/2;
        }
    }
    
    double getKth(int A[],int starta,int sizea, int B[], int startb,int sizeb, int k)
    {
        assert(A&&B);
        //here k is not index, but the k-th element
        if(sizea<=0) return B[startb+k-1];
        if(sizeb<=0) return A[starta+k-1];
        if(k<=1) return min(A[starta],B[startb]);
        
        int meda=sizea/2+1;
        int medb=sizeb/2+1;
        int med=sizea/2+sizeb/2+1;
        
        if(A[starta+meda-1]>=B[startb+medb-1])
        {
            if(k>med)
                return getKth(A,starta,sizea,B,startb+medb,sizeb-medb,k-medb);
            else
                return getKth(A,starta,meda-1,B,startb,sizeb,k);
        }
        else{
            if(k>med)
                return getKth(A,starta+meda,sizea-meda,B,startb,sizeb,k-meda);
            else
                return getKth(A,starta,sizea,B,startb,medb-1,k);
        }
    }
};