LeetCode 643. 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 <= k <= n <= 30,000.
Elements of the given array will be in the range [-10,000, 10,000].

题目大意:给定一个由n个整数组成的数组,找到具有最大平均值的给定长度k的连续子数组。你需要输出最大的平均值~

分析:sum[i]保存0~i个数字的和,每次将(sum[i]-sum[i-k])的最大值保存在ans中,然后返回ans*1.0/k