643.子数组最大平均数I

方法：滑动窗口

class Solution {
    public double findMaxAverage(int[] nums, int k) {
        int n = nums.length;
        int winSum = 0;
        //先求出第一个窗口的和
        for(int i = 0;i<k;i++){
            winSum += nums[i];
        }
        //通过遍历求出除了第一窗口的和
        int res = winSum;
        for(int i = k;i<n;i++){
            winSum = winSum + nums[i] - nums[i - k];
            res = Math.max(winSum,res);
        }
        return (double) res / k;

    }
}