segmentation fault 11 in C++ code

Question

for my bucket sort, I don't know why the out put is segmentation fault: 11 when I try to print out sorted distance. It should be running well on win pc, but I try running it on mac, but i just get error. where am I wrong?

using namespace std;
void bucketSort(vector<double> &arr, int n)
{
    vector<double> distance;
    vector<double> b[n];

    for (int i=1; i<=n/2; i++)
    {
    double c = sqrt(i)/sqrt(n/2);
    cout<<c<<endl;
    }

    for (int i=0; i<n; i++)
    {
    double dist = sqrt(pow((arr[i]-0), 2) + pow((arr[i+1]-0), 2));
    i = i+1;
    distance.push_back(dist);
    }

    for (int i=0; i<n; i++)
    {
    int bi = n*distance[i]; // Index in bucket
       b[bi].push_back(distance[i]);
    }

    for (int i=0; i<n; i++)
    {
    sort(b[i].begin(), b[i].end());
    }

    int index = 0;
    for (int i = 0; i < n; i++)
    {
    for (int j = 0; j < b[i].size(); j++)
    {
        distance[index++] = b[i][j];
    }
    }

    for (int i = 0; i < n/2; i++)
    {
    cout<<distance[i]<<endl;
    }
}
int main()
{
    vector<double> A;

    double numbers;

    while (cin>>numbers)
    {
    A.push_back(numbers);
    }

    int n = A.size();
    bucketSort(A, n);
}

Here is the out put:

Claudes-MBP:desktop BengDai$ ./a.out < n.txt
0.5
0.707107
0.866025
1
Segmentation fault: 11
Claudes-MBP:desktop BengDai$ 

Answer 1

In your code you use arr[i+1] in a loop where is in the range 0 to n-1.

This means you will try and use arr[n] which is beyond the end of the array.

This block is also suspect:

for (int i=0; i<n; i++)
    {
    int bi = n*distance[i]; // Index in bucket
       b[bi].push_back(distance[i]);
    }

b[bi] : The value of bi could be bigger than the array size of b and probably is?