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].

求在一个范围内的和的最大值，相当于移动一个窗口，求这个窗口里的最大的值，蛮简单的，注意细节

class Solution {
public:
    double findMaxAverage(vector<int>& nums, int k) {

        int n = nums.size();
        int tmp = INT_MIN, res = INT_MIN;
        if (n <= k)
        {
            return accumulate(nums.begin(), nums.end(), 0) / (double)k;
        }

        tmp = accumulate(nums.begin(), nums.begin() + k, 0);
        res = max(res, tmp);
        for (int i = k; i < n; ++i)
        {
            tmp = tmp + nums[i] - nums[i - k];
            res = max(res, tmp);
        }

        return res / (double)k;

    }
};