ПРОШУ помогите с++

 #include <iostream> 
#include <unordered_map> 
 
int countPairsWithSumX(int arr[], int n, int X) { 
    std::unordered_map<int, int> freqMap; 
    int pairCount = 0; 
     
    for (int i = 0; i < n; i++) { 
        int complement = X - arr[i]; 
        if (freqMap.find(complement)!= freqMap.end()) { 
            pairCount += freqMap[complement]; 
        } 
        freqMap[arr[i]]++; 
    } 
     
    return pairCount; 
} 
 
int main() { 
    int testCaseNum; 
    std::cin >> testCaseNum; 
     
    for (int testCase = 0; testCase < testCaseNum; testCase++) { 
        int n; 
        std::cin >> n; 
         
        int arr[n]; 
        for (int i = 0; i < n; i++) { 
            std::cin >> arr[i]; 
        } 
         
        int X;  
        std::cin >> X; 
         
        int result = countPairsWithSumX(arr, n, X); 
        std::cout << result << std::endl; 
    } 
     
    return 0; 
} 

 #include <iostream> 
#include <vector> 
 
using namespace std; 
 
struct Pair { 
    using num_t = long; 
    using sum_t = long long; 
    num_t a; 
    num_t b; 
    bool matches(const sum_t k) const { 
        return (sum_t)a + (sum_t)b == k; 
    } 
}; 
 
class Task { 
public: 
    Task(const vector<Pair::num_t>& present) { 
        const size_t n = present.size(); 
        const auto m = n - 1; 
        for (size_t i = 0; i < m; ++i) { 
            for (size_t j = i + 1; j < n; ++j) { 
                pairs.emplace_back(Pair{ present[i], present[j] }); 
            } 
        } 
    } 
    size_t count(const Pair::sum_t k) const { 
        size_t quantity = 0; 
        for (const auto& item : pairs) { 
            if (item.matches(k)) { 
                ++quantity; 
            } 
        } 
        return quantity; 
    } 
private: 
    vector<Pair> pairs; 
}; 
int main() { 
    size_t i = 0, t; 
    cin >> t; 
    vector<size_t> results(t); 
    while (i < t) { 
        size_t n; 
        cin >> n; 
        Pair::sum_t k; 
        cin >> k; 
        vector<Pair::num_t> present(n); 
        for (auto& number : present) cin >> number; 
        Task task(present); 
        results[i] = task.count(k); 
        ++i; 
    } 
    for (auto result : results) { 
        cout << result << '\n'; 
    } 
}