Maximum Average Subarray I --最大的连续数平均

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].  

题意：找出连续k个数的平均值最大；

思路：从头开始遍历，先把前四位相加，再从k位开始，每次加上后一位减去前一位，把最大值存在result上；

代码实现如下：

class Solution {
    public double findMaxAverage(int[] nums, int k) {
        long sum = 0;
        for (int i = 0; i < k; i++) sum += nums[i];
        long max = sum;
        
        for (int i = k; i < nums.length; i++) {
            sum += nums[i] - nums[i - k];
            max = Math.max(max, sum);
        }
        
        return max / 1.0 / k;
}
}