LeetCode Entry

2348. Number of Zero-Filled Subarrays

19.08.2025 medium 2025 kotlin rust

Count 0-subarrays

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Problem TLDR

Count 0-subarrays #medium #counting

Intuition

Count zero islands, use arithmetic sum: n(n+1)/2

Approach

  • instead of arithmetics, just add current count to the result

Complexity

  • Time complexity: \(O(n)\)

  • Space complexity: \(O(1)\)

Code


// 5ms
    fun zeroFilledSubarray(n: IntArray) =
        n.fold(0L) { r, t ->
            if (t == 0) ++n[0] else n[0] = 0; r + n[0]
        }



// 3ms
    fun zeroFilledSubarray(n: IntArray): Long {
        var res = 0L; var curr = 0
        for (x in n) {
            if (x == 0) ++curr else curr = 0
            res += curr
        }
        return res
    }



// 0ms
    pub fn zero_filled_subarray(n: Vec<i32>) -> i64 {
        let (mut r, mut c) = (0, 0);
        for x in n { if (x == 0) { c += 1 } else { c = 0 }; r += c } r
    }



// 0ms
    long long zeroFilledSubarray(vector<int>& n) {
        long long r = 0;
        for (int c = 0; int x: n) r += c = x ? 0: ++c;
        return r;
    }



// 49ms
    zeroFilledSubarray = lambda _,n: sum(accumulate(n, lambda c,x: (c+1)*(x==0), initial=0))