Bouncing Ball

#include <iostream>
#include <vector>
#include <numeric>
#include <cmath>

class Analyzer {
    std::vector<int> sequence, prefixSum, suffixSum;

    void calculateSums() {
        prefixSum = suffixSum = sequence;
        std::partial_sum(sequence.begin(), sequence.end(), prefixSum.begin());
        std::partial_sum(sequence.rbegin(), sequence.rend(), suffixSum.rbegin());
    }

    int findOptions() {
        int options = 0;
        for (size_t dx = 0; dx < sequence.size(); ++dx) {
            if (sequence[dx] == 0) {
                int leftSum = dx ? prefixSum[dx - 1] : 0;
                int rightSum = dx < sequence.size() - 1 ? suffixSum[dx + 1] : 0;
                options += (leftSum == rightSum) ? 2 : (std::abs(leftSum - rightSum) == 1);
            }
        }
        return options;
    }

public:
    void handleTest() {
        int length;
        std::cin >> length;
        sequence.resize(length);
        for (int &value : sequence) {
            std::cin >> value;
        }
        calculateSums();
        std::cout << findOptions() << '\n';
    }
};

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int testCases;
    std::cin >> testCases;
    Analyzer analyzer;
    while (testCases--) {
        analyzer.handleTest();
    }
    return 0;
}