leetcode 4. Median of Two Sorted Arrays

给了两个排好序的数组，如果再去把数组合并排序找中间数肯定超时。

这里分别从左端开始比较两个数组，当前个数k=0,i=j=0,如果array1[i]<=array2[j],i++,k++,当k为想要的中间数把它保存；

class Solution {
public:
        double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
            int k=0,i=0,j=0;
            int n1=nums1.size(),n2=nums2.size();
            vector<int>a;
            if(n1+n2==1){
               if(!n1)
                   return nums2[0];
                else return nums1[0];
            }
            while(i<n1&&j<n2)
            {
              double num;
              if(nums1[i]<=nums2[j]){
                 num=nums1[i];
                 i++;
              }
              else {
                   num=nums2[j];
                  j++;
                   }
                if(k==(n1+n2)/2||k==(n1+n2)/2-1)
                    a.push_back(num);
             k++;
            }
            while(i<n1)
            {
              if(k==(n1+n2)/2||k==(n1+n2)/2-1)
                    a.push_back(nums1[i]);
                i++;
                k++;
            }
            while(j<n2)
            {
              if(k==(n1+n2)/2||k==(n1+n2)/2-1)
                    a.push_back(nums2[j]);
                j++;
                k++;
            }
            if((n1+n2)&1)
                return a[1];
            else
                return (a[0]+a[1])/2.0;
        }
};