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radixsort.cpp
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radixsort.cpp
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/*
* g++ -Wall -O2 -std=c++11 -o radixsort.exe radixsort.cpp
*/
#include <iostream>
#include <iomanip>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#define LIMIT 4000
using namespace std;
// http://cubic.org/docs/radix.htm
void radix (int byte, long N, long *source, long *dest)
{
long count[1024];
long index[1024];
int i;
memset (count, 0, sizeof (count));
for ( i=0; i<N; i++ ) count[((source[i])>>(byte*8))&0xff]++;
index[0]=0;
for ( i=1; i<1024; i++ )
index[i]=index[i-1]+count[i-1];
for ( i=0; i<N; i++ )
dest[index[((source[i])>>(byte*8))&0xff]++] = source[i];
}
void radixsort (long *source, long *temp, long N)
{
radix (0, N, source, temp);
radix (1, N, temp, source);
radix (2, N, source, temp);
radix (3, N, temp, source);
}
void make_random (long *data, long N)
{
srand(time(NULL));
for ( int i=0; i<N; i++ )
{
data[i]=rand() % LIMIT;
cout << setw(5) << data[i] << " ";
//printf("%5d", data[i]);
}
cout << "\n\n\n";
}
long data[LIMIT];
long temp[LIMIT];
int main (void)
{
make_random(data, LIMIT);
radixsort (data, temp, LIMIT);
for ( int i=0; i<LIMIT; i++ )
cout << setw(5) << data[i];
//printf("%5d", data[i]);
cout << endl;
return 0;
}