Question

IN C++:

Create sets of 1 Million integers with the following characteristics;
Sets where no numbers repeat
Sets where the range of numbers is 1% of the array size
Sets where no numbers repeat and each integer has 20 digits

Create Radixsort

Answer 1

// C++ implementation of Radix Sort
#include<iostream>
using namespace std;

// A utility function to get maximum value in arr[]
int getMax(int arr[], int n)
{
   int mx = arr[0];
   for (int i = 1; i < n; i++)
       if (arr[i] > mx)
           mx = arr[i];
   return mx;
}

// A function to do counting sort of arr[] according to
// the digit represented by exp.
void countSort(int arr[], int n, int exp)
{
   int output[n]; // output array
   int i, count[10] = {0};

   // Store count of occurrences in count[]
   for (i = 0; i < n; i++)
       count[ (arr[i]/exp)%10 ]++;

   // Change count[i] so that count[i] now contains actual
   // position of this digit in output[]
   for (i = 1; i < 10; i++)
       count[i] += count[i - 1];

   // Build the output array
   for (i = n - 1; i >= 0; i--)
   {
       output[count[ (arr[i]/exp)%10 ] - 1] = arr[i];
       count[ (arr[i]/exp)%10 ]--;
   }

   // Copy the output array to arr[], so that arr[] now
   // contains sorted numbers according to current digit
   for (i = 0; i < n; i++)
       arr[i] = output[i];
}

// The main function to that sorts arr[] of size n using
// Radix Sort
void radixsort(int arr[], int n)
{
   // Find the maximum number to know number of digits
   int m = getMax(arr, n);

   // Do counting sort for every digit. Note that instead
   // of passing digit number, exp is passed. exp is 10^i
   // where i is current digit number
   for (int exp = 1; m/exp > 0; exp *= 10)
       countSort(arr, n, exp);
}

// A utility function to print an array
void print(int arr[], int n)
{
   for (int i = 0; i < n; i++)
       cout << arr[i] << " ";
}

// Driver program to test above functions
int main()
{
   int arr[] = {170, 45, 75, 90, 802, 24, 2, 66};
   int n = sizeof(arr)/sizeof(arr[0]);
   radixsort(arr, n);
   print(arr, n);
   return 0;
}