题目如下:
Given an array of integers
arr
and two integersk
andthreshold
.Return the number of sub-arrays of size
k
and average greater than or equal tothreshold
.Example 1:
Input: arr = [2,2,2,2,5,5,5,8], k = 3, threshold = 4 Output: 3 Explanation: Sub-arrays [2,5,5],[5,5,5] and [5,5,8] have averages 4, 5 and 6 respectively. All other sub-arrays of size 3 have averages less than 4 (the threshold).Example 2:
Input: arr = [1,1,1,1,1], k = 1, threshold = 0 Output: 5Example 3:
Input: arr = [11,13,17,23,29,31,7,5,2,3], k = 3, threshold = 5 Output: 6 Explanation: The first 6 sub-arrays of size 3 have averages greater than 5. Note that averages are not integers.Example 4:
Input: arr = [7,7,7,7,7,7,7], k = 7, threshold = 7 Output: 1Example 5:
Input: arr = [4,4,4,4], k = 4, threshold = 1 Output: 1Constraints:
1 <= arr.length <= 10^5
1 <= arr[i] <= 10^4
1 <= k <= arr.length
0 <= threshold <= 10^4
解题思路:滑动窗口问题,把每一个区间的和都算出来吧。
代码如下:
class Solution(object): def numOfSubarrays(self, arr, k, threshold): """ :type arr: List[int] :type k: int :type threshold: int :rtype: int """ res = 0 count = 0 for i in range(len(arr)): if i < k - 1 : count += arr[i] elif i == k - 1: count += arr[i] if count / k >= threshold: res += 1 else: count += arr[i] count -= arr[i-k] if count / k >= threshold: res += 1 return res