NumberOfDiscIntersections2

// you can use includes, for example:
#include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

struct Interval {
    long left;
    long right;
};

inline bool mySortFunction(Interval p1, Interval p2) {
    return ( p1.left < p2.left );
}

int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    if (A.empty()) {
        return 0;
    }
    
    vector<Interval> arr;

    for (size_t i = 0; i < A.size(); ++i) {
        arr.push_back({ (long)(i - A[i]), long(i + A[i]) });
    }
    
    std::sort(arr.begin(), arr.end(), mySortFunction);

    int result = 0;
    for (size_t i = 0; i < arr.size(); ++i) {
        for (size_t j = i + 1; j < arr.size(); ++j)
        {
            if (arr[j].left > arr[i].right) {
                break;
            }
            
            if (++result > 10000000) {
                return -1;
            }  
        }
    }
    return result;
}