643. Maximum Average Subarray I

 static int wing=[]()
 {
     std::ios::sync_with_stdio(false);
     cin.tie(NULL);
     return ;
 }();
 
 class Solution
 {
 public:
     double findMaxAverage(vector<int>& nums, int k)
     {
         int sz=nums.size();
         double maxsum=0.0;
         double cursum=0.0;
         for(int i=;i<k;i++)
             cursum+=nums[i];
         maxsum=cursum;
         for(int j=k;j<sz;j++)
         {
             cursum=cursum-nums[j-k]+nums[j];
             maxsum=max(cursum,maxsum);
         }
         return maxsum/k;
     }
 };

扫描一遍，更新当前和，最大和，最后取走最大和即可