SimpleNonRepeatRandomNG.cpp

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#include "SimpleNonRepeatRandomNG.h"
#include "RandomEngine.h"
#include "PCSIMException.h"

#include <algorithm>
#include <limits>

using std::swap;


SimpleNonRepeatRandomNG::SimpleNonRepeatRandomNG()
   : seq_array(NULL), cursor(0), unidist(0, 1) 
{
        
}

SimpleNonRepeatRandomNG::SimpleNonRepeatRandomNG(int low, int high)
   : low(low), high(high), cursor(0), unidist(0, 1)
{
        range = high - low + 1;
    seq_array = new int[high-low+1];
    for (int i = 0; i < range; ++i)
        seq_array[i] = i;
}

SimpleNonRepeatRandomNG::~SimpleNonRepeatRandomNG()
{
        if (seq_array) 
        delete [] seq_array;
}

int SimpleNonRepeatRandomNG::operator()( RandomEngine &eng )
{
    if (cursor > num_elem) {
        throw PCSIM::Exception("SimpleNonRepeatRandomNG::operator()", "ERROR: Tried to generate more random numbers than num_elem");
    }
    int n = int( unidist( eng ) * (range - cursor) );
    // n = n % (range - cursor);
    int rand_num = seq_array[cursor + n];
    swap(seq_array[cursor], seq_array[cursor + n]);
    generated_numbers.push_back(n);
    cursor++;
    return low + rand_num;
}

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