记载出现从头到目前为止出现t个奇数的个数

class Solution:
    def numberOfSubarrays(self, nums: List[int], k: int) -> int:
        d = collections.defaultdict(int)
        ans, t, d[0] = 0, 0, 1
        for n in nums:
            if n % 2 == 1:
                t += 1
            d[t] += 1
            ans += d[t-k]
        return ans