Generating random numbers in reverse order???

[dav3]

I have almost completed a monster assignment on sorting algorithms (quick, insertion and selection) using c++ but I am lost on one part of the assignment. I have to generate a random list of numbers in reverse order as follows "list[i] = 25.88 - sqrt(i)" and perform all my sorting functions no this list. I have successfully run my program on numerous lists of random numbers.. I just have no clue how to get a reverse generated list of random numbers.

Any help is appreciated. Thanks.

[dav3]

still looking for any help on this. Its got me bamboozeled.

[sicarie]

still looking for any help on this. Its got me bamboozeled.

Are you sure you need a list of random numbers? Anything where you have a set seed value and algorithm to produce the number will not be a "random" number.

But it sounds like you need to perform the operation 25 times, with i being 25->0.

[macklin01]

I'm not entirely sure what you're asking for.

Do you want a list of random numbers, but each successive number should be smaller? e.g.,


1239.295
99.482
83.218
47.671
14.23148
12.184
11.19847
8.193
8.0582
6.2

etc.?

Well, here's the simplest way I can think of to do that:

float largest_number = 10000;
float scale = largest_number;

for( int i=0; i < total_count ; i++ )
{
list[i] = scale * rand() / (float) RAND_MAX;
scale = list[i];
}

In this way, the next random number will be between 0 and the previous number.

Is this the type of thing that you're looking for? -- Paul

[dav3]

After emailing my instructor it seems I am supposed to generate the list as follows

list[0] = 25.88 - sqrt(0) = 25.88
list[1] = 25.88 - sqrt(1) = 24.88
list[2] = 25.88 - sqrt(2) = 24.4658

however I am having issues getting my program running. I get this error and am not sure what to make of it

Error 1 error C2676: binary '[' : 'orderedArrayListType<elemType>' does not define this operator or a conversion to a type acceptable to the predefined operator

The code that generates said error is this:

#include "stdafx.h"
#include <iostream>
#include "orderedArrayListType.h"
#include <time.h>
#include <math.h>
using namespace std;
 
//double sqrt(double, double);
 
int _tmain(int argc, _TCHAR* argv[])
{
    double i;
 
    int maxSize;
 
    cout << "Please enter the size of the list: 10, 100 or 1000"<<endl;
    cin >> maxSize;    //User determined size of list
 
    cout<<"Testing selection sort!!!"<<endl;
    orderedArrayListType<int>list(maxSize);     
    cout<<"Size of list = "<<list.maxListSize();
 
    for(i = 0; i < maxSize; i++)
    {
        list[i] = 25.88 - sqrt(i);
    }
 
        cout<<"The list before sorting:"<<endl;    
        list.print();                                    
        cout<<endl;                                        
 
        list.selectionSort();    
 
        cout<<"The list after sorting:"<<endl;    
        list.print();                                    
        cout<<endl;                                        
 
        cout << "Selection sort: Number of comparisons = "<<list.getSortComparisons()<<endl;
        cout << "Selection sort: Number of swaps = "<<list.getSortSwaps()<<endl;
        cout<<endl;
 
 
    return 0;
}
 

The specific line where the problem is

for(i = 0; i < maxSize; i++)
    {
        list[i] = 25.88 - sqrt(i);
    }
 

[dav3]

found my mistake. Thank you all who gave advice:)