Bucket sort and User input - c++

Question

Here's the problem I'm working on: a user gives me an unspecified number of points on a standard x,y coordinate plane, where 0 < x^2 + y^2 <= 1. (x squared plus y squared, just for clarity).
Here is an example of the input:
0.2 0.38
0.6516 -0.1
-0.3 0.41
-0.38 0.2
From there, I calculate the distance of those points from the origin, (0, 0). Here is the function I use to find the distance and push it into a vector of doubles, B.
void findDistance(double x = 0, double y = 0) {
double x2 = pow(x, 2);
double y2 = pow(y, 2);
double z = x2 + y2;
double final = sqrt(z);
B.push_back(final);
}
Then, I want to bucket sort vector B, where there are n buckets for n points. Here is my current build of the bucketSort:
void bucketSort(double arr[], int n)
{
vector<double> b[n];
for (int i=0; i<n; i++)
{
int bi = n*arr[i];
b[bi].push_back(arr[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++)
arr[index++] = b[i][j];
}
My problem is I can't get bucketSort to work without crashing. I get a windows message saying the program has stopped working. Now, I know the function works, but only when I initialize the vector and fill it at the same time. This is an example of a call that works:
double arr[] = {0.707107, 0.565685, 0.989949, 0.848528 };
int n = sizeof(arr)/sizeof(arr[0]);
bucketSort(arr, n);
So far, I've yet to find any other format for calling and initializing the vector that the function will accept and run. I need to find a way to take the points, computer the distances, and sort the distances. Current main that I'm plugging in and getting as a backfire:
int main(){
int number;
while (cin >> number){
A.push_back(number); }
int q = 0; double r = 0; double d = 0;
while (q < (A.size() - 1)){
findDistance(A[q], A[q+1]);
q += 2;
}
double arr[B.size()]; copy(B.begin(), B.end(), arr);
int n = (sizeof(B) + sizeof(B[0])) / sizeof(B[0]);
bucketSort(arr, n);
int w = 0;
while (w < y){ cout << arr[w] << endl; w++; }
The arr copy was created in some strange debugging attempt: sorry if unclear. Results of distance function stored in B, copied into arr, and arr is what's attempted to be sorted. The user inputs are given through the command prompt, using the syntax listed in the beginning. Output should be something like:
0.42941
0.49241
0.50804
0.65923
If anyone can offer suggestions of edits to either of functions that would make it work, the assistance would be greatly appreciated.

Answer 1

Here are a few issues to work on:
Your input loop will stop when it reads a non-integer. Change number to double
Your size calculation
int n = (sizeof(B) + sizeof(B[0])) / sizeof(B[0]);
I am not sure what you are trying to do here, but sizeof on a vector is not what you want. I think replacing this with:
int n = B.size();
is what you want.
I am not sure why you needed to convert the vector to an array to do the bucket sort - much easier to just pass the vector through to the bucket sort, then the size comes with the vector.
Change the bucketSort function to take a reference to a vector:
void bucketSort(vector<double> &arr)
{
int n = B.size();
...
and just pass B into the function. The rest of the code should be the same.
Also a portability note: not every compiler supports variable sized arrays, you are better off sticking with vector wherever possible.