Maximum Average Subarray I

Given an array consisting of n integers, find the contiguous subarray of given length k that has the maximum average value. And you need to output the maximum average value.

Example 1:

Input: [1,12,-5,-6,50,3], k = 4
Output: 12.75
Explanation: Maximum average is (12-5-6+50)/4 = 51/4 = 12.75

 

Note:

  1. 1 <= k <= n <= 30,000.
  2. Elements of the given array will be in the range [-10,000, 10,000].

Solution:

class Solution {
    public double findMaxAverage(int[] nums, int k) {
        int left = 0, right = 0, n = nums.length;
        double max = -10000.0, sum = 0.0;
        while (right < n) {
            int in = nums[right];
            sum += in;
            if (right - left + 1 > k) {
                int out = nums[left ++];
                sum -= out;
            }
            if (right - left + 1 == k) {
                double avg = sum / k;                
                max = Math.max(max, avg);
            }
            right ++;
        }
        return max;
    }
}