Maximum Average Subarray I

Question

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].

Tags

• Array

Thought

Notice: Don't sum the subarray every time, because it is very inefficient and will cause TLE.

Code

class Solution(object):
    def findMaxAverage(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: float
        """
        tmpSum = sum(nums[:k])
        maxSum = tmpSum
        for i in xrange(len(nums) - k):
            j = i + k
            tmpSum = tmpSum - nums[i] + nums[j]
            maxSum = max(maxSum, tmpSum)
        return maxSum / float(k)