Gaussian sort

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <thread>
using namespace std;
const size_t size=50000000;
void s(double ** bucketsstart, double** bucketsend, int start,int delta, int numbuckets){
    for (;start<=numbuckets; start+=delta)
        sort(bucketsstart[start],bucketsend[start]);
}
int main(){
    double *data=new double[size];
    FILE *f = fopen("gaussian.dat", "rb");
    fread(data,8,size,f);
    FILE* h=fopen("helper.txt","rb");
    int numbuckets;
    fread(&numbuckets,sizeof(int),1,h);
    int dscale;
    fread(&dscale,sizeof(int),1,h);
    double dmin; //minimum value of tabularised distribution
    double dmax; //,aximum ditto
    fread(&dmin,sizeof(double),1,h);
    fread(&dmax,sizeof(double),1,h);
    //int minn=dmin*dscale;
    int ile;
    fread(&ile,sizeof(int),1,h);
    int *tab=new int[ile];
    int test=fread(tab,sizeof(int),ile,h);
    if (test!=ile) cout<<"blad\n";
    double * databuckets=new double [size*4+size/numbuckets*4]; //just to be sure
    double ** bucketsstart= new double* [numbuckets+1];// pointer to beggining of every bucket
    double ** bucketsend= new double* [numbuckets+1]; //pointer to end
    int offset=4*size/numbuckets;
    for (int i=0; i<numbuckets+1; i++){
        bucketsend[i]=bucketsstart[i]=databuckets+i*offset;
    }
    for (int i=0; i<size; i++){
        if (data[i]>dmax) {
            *bucketsend[numbuckets]++=data[i];
        }
        else if (data[i]<dmin) *bucketsend[0]++=data[i];
        else {
            *bucketsend[tab[(int)((data[i]-dmin)*dscale)]]++=data[i];
        }
    }
    const int numthreads=4;
    thread** thr=new thread*[numthreads];
    for (int i=0; i<numthreads; i++){
        thr[i] =new thread (s,bucketsstart,bucketsend,i,numthreads,numbuckets);
    }
    for (int i=0; i<numthreads; i++){
        thr[i]->join();
        delete thr[i];
    }
    delete [] thr;
    double* currData=data;
    for (int i=0; i<=numbuckets; i++){
        memcpy(currData,bucketsstart[i],(bucketsend[i]-bucketsstart[i])*8);
        currData+=bucketsend[i]-bucketsstart[i];
    }
    //for (int i=0; i<size-1; i++){
    //  if (data[i]>data[i+1]) cout<<i<<' '<<data[i]<<' '<<data[i+1]<<endl;
    //}

    //fwrite(data,8,size,stdout);
    fclose(h);
    fclose(f);
}