leetcode 4. 寻找两个正序数组的中位数 二分

class Solution {
    public double findMedianSortedArrays(int[] nums1, int[] nums2) {
       int len1=nums1.length,len2=nums2.length;
       int total=len1+len2;
       if(total%2==1)
       {
    	   return getk(nums1,nums2,total/2+1);
       }
       else
       {
    	   return (getk(nums1,nums2,total/2)+getk(nums1,nums2,total/2+1))/2.0;
       }
    }

   public double getk(int []a,int []b,int k)
   {
	   int lena=a.length;
	   int lenb=b.length;
	   int idxa=0,idxb=0;
	   
	   
	   while(true)
	   {
		   if(idxa==lena)return b[idxb+k-1];
		   if(idxb==lenb)return a[idxa+k-1];
		   if(k==1)return Math.min(a[idxa], b[idxb]);
		   
		   int newidxa=Math.min(lena-1, idxa+k/2-1);
		   int newidxb=Math.min(lenb-1, idxb+k/2-1);
		   
		   int p1=a[newidxa];int p2=b[newidxb];
		   if(p1<=p2)
		   {
			   k-=(newidxa-idxa+1);
			   idxa=newidxa+1;
		   }
		   else
		   {
			   k-=(newidxb-idxb+1);
			   idxb=newidxb+1;
		   }
	   }
   }
}