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Gaussian sort

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Jun 9th, 2011
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  1. #include <cstdio>
  2. #include <cstring>
  3. #include <cstdlib>
  4. #include <iostream>
  5. #include <algorithm>
  6. #include <thread>
  7. using namespace std;
  8. const size_t size=50000000;
  9. void s(double ** bucketsstart, double** bucketsend, int start,int delta, int numbuckets){
  10.     for (;start<=numbuckets; start+=delta)
  11.         sort(bucketsstart[start],bucketsend[start]);
  12. }
  13. int main(){
  14.     double *data=new double[size];
  15.     FILE *f = fopen("gaussian.dat", "rb");
  16.     fread(data,8,size,f);
  17.     FILE* h=fopen("helper.txt","rb");
  18.     int numbuckets;
  19.     fread(&numbuckets,sizeof(int),1,h);
  20.     int dscale;
  21.     fread(&dscale,sizeof(int),1,h);
  22.     double dmin; //minimum value of tabularised distribution
  23.     double dmax; //,aximum ditto
  24.     fread(&dmin,sizeof(double),1,h);
  25.     fread(&dmax,sizeof(double),1,h);
  26.     //int minn=dmin*dscale;
  27.     int ile;
  28.     fread(&ile,sizeof(int),1,h);
  29.     int *tab=new int[ile];
  30.     int test=fread(tab,sizeof(int),ile,h);
  31.     if (test!=ile) cout<<"blad\n";
  32.     double * databuckets=new double [size*4+size/numbuckets*4]; //just to be sure
  33.     double ** bucketsstart= new double* [numbuckets+1];// pointer to beggining of every bucket
  34.     double ** bucketsend= new double* [numbuckets+1]; //pointer to end
  35.     int offset=4*size/numbuckets;
  36.     for (int i=0; i<numbuckets+1; i++){
  37.         bucketsend[i]=bucketsstart[i]=databuckets+i*offset;
  38.     }
  39.     for (int i=0; i<size; i++){
  40.         if (data[i]>dmax) {
  41.             *bucketsend[numbuckets]++=data[i];
  42.         }
  43.         else if (data[i]<dmin) *bucketsend[0]++=data[i];
  44.         else {
  45.             *bucketsend[tab[(int)((data[i]-dmin)*dscale)]]++=data[i];
  46.         }
  47.     }
  48.     const int numthreads=4;
  49.     thread** thr=new thread*[numthreads];
  50.     for (int i=0; i<numthreads; i++){
  51.         thr[i] =new thread (s,bucketsstart,bucketsend,i,numthreads,numbuckets);
  52.     }
  53.     for (int i=0; i<numthreads; i++){
  54.         thr[i]->join();
  55.         delete thr[i];
  56.     }
  57.     delete [] thr;
  58.     double* currData=data;
  59.     for (int i=0; i<=numbuckets; i++){
  60.         memcpy(currData,bucketsstart[i],(bucketsend[i]-bucketsstart[i])*8);
  61.         currData+=bucketsend[i]-bucketsstart[i];
  62.     }
  63.     //for (int i=0; i<size-1; i++){
  64.     //  if (data[i]>data[i+1]) cout<<i<<' '<<data[i]<<' '<<data[i+1]<<endl;
  65.     //}
  66.  
  67.     //fwrite(data,8,size,stdout);
  68.     fclose(h);
  69.     fclose(f);
  70. }
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