Window Sum（sliding window)

Description

Given an array of n integers, and a moving window(size k), move the window at each iteration from the start of the array, find thesumof the element inside the window at each moving.

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Problem Correction

Example

For array[1,2,7,8,5], moving window size k =3. 1 + 2 + 7 = 10 2 + 7 + 8 = 17 7 + 8 + 5 = 20 return[10,17,20]

分析

还是loop len,然后count ++/--

class Solution:
    """
    @param nums: a list of integers.
    @param k: length of window.
    @return: the sum of the element inside the window at each moving.
    """
    def winSum(self, nums, k):
        # write your code here
        sum  = 0
        res = []
        cnt = 0
        nlen = len(nums)
        for i in range(nlen):
            sum += nums[i]
            cnt += 1
            if cnt > k:
                sum -= nums[i - k]
                cnt -= 1
            if cnt == k:
                res.append(sum)
        return res