leetcode 643. Maximum Average Subarray I

1.题目

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.
给一个长度为n的数组，求长度为k的平均值最大的连续子数组

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].

2.分析

滑动窗口求平均值

3.代码

double findMaxAverage(vector<int>& nums, int k) {    long long* ksum = new long long[nums.size() - k + 1]();    for (int i = 0; i < k; i++)        ksum[0] += nums[i];    long long maxS = ksum[0];    for (int i = 1; i <= nums.size() - k; i++) {        ksum[i] = ksum[i - 1] + nums[i + k - 1] - nums[i - 1];        maxS = maxS > ksum[i] ? maxS : ksum[i];    }    return (double)maxS / k;}