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].
思路就是sliding windows, A[i] = A[i-1] - nums[i-1] + nums[i+k-1], init: A[0] = sum(nums[:k])
Code: T: O(n) S; O(1) using rolling arry to O(1)
class Solution(object): def findMaxAverage(self, nums, k): ans, n = sum(nums[:k]), len(nums) dp = [ans] + [0] for i in range(1, n-k+1): dp[i%2] = dp[i%2-1] - nums[i-1] + nums[i+k-1] ans = max(ans, dp[i%2]) return ans*1.0/k