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2348. Number of Zero-Filled Subarrays

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Description

Given an integer array nums, return the number of subarrays filled with 0.

A subarray is a contiguous non-empty sequence of elements within an array.

 

Example 1:

Input: nums = [1,3,0,0,2,0,0,4]
Output: 6
Explanation: 
There are 4 occurrences of [0] as a subarray.
There are 2 occurrences of [0,0] as a subarray.
There is no occurrence of a subarray with a size more than 2 filled with 0. Therefore, we return 6.

Example 2:

Input: nums = [0,0,0,2,0,0]
Output: 9
Explanation:
There are 5 occurrences of [0] as a subarray.
There are 3 occurrences of [0,0] as a subarray.
There is 1 occurrence of [0,0,0] as a subarray.
There is no occurrence of a subarray with a size more than 3 filled with 0. Therefore, we return 9.

Example 3:

Input: nums = [2,10,2019]
Output: 0
Explanation: There is no subarray filled with 0. Therefore, we return 0.

 

Constraints:

• 1 <= nums.length <= 105
• -109 <= nums[i] <= 109

Solutions

Python3

class Solution:
    def zeroFilledSubarray(self, nums: List[int]) -> int:
        ans = 0
        cnt = 0
        for v in nums:
            if v == 0:
                cnt += 1
            else:
                ans += (1 + cnt) * cnt // 2
                cnt = 0
        ans += (1 + cnt) * cnt // 2
        return ans

Java

class Solution {
    public long zeroFilledSubarray(int[] nums) {
        long ans = 0;
        int cnt = 0;
        for (int v : nums) {
            if (v == 0) {
                ++cnt;
            } else {
                ans += (long) (1 + cnt) * cnt / 2;
                cnt = 0;
            }
        }
        ans += (long) (1 + cnt) * cnt / 2;
        return ans;
    }
}

C++

class Solution {
public:
    long long zeroFilledSubarray(vector<int>& nums) {
        long long ans = 0;
        int cnt = 0;
        for (int v : nums) {
            if (v == 0)
                ++cnt;
            else {
                ans += 1ll * (1 + cnt) * cnt / 2;
                cnt = 0;
            }
        }
        ans += 1ll * (1 + cnt) * cnt / 2;
        return ans;
    }
};

Go

func zeroFilledSubarray(nums []int) int64 {
	ans := 0
	cnt := 0
	for _, v := range nums {
		if v == 0 {
			cnt++
		} else {
			ans += (1 + cnt) * cnt / 2
			cnt = 0
		}
	}
	ans += (1 + cnt) * cnt / 2
	return int64(ans)
}

TypeScript

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