Implementation to sort an array of size n where elements are in range from 0 to n2 – 1.
// A function to do counting sort of arr[] according to
// the digit represented by exp.
int countSort(int arr[], int n, int exp)
{
int output[n]; // output array
int i, count[n] ;
for (int i=0; i < n; i++)
count[i] = 0;
// Store count of occurrences in count[]
for (i = 0; i < n; i++)
count[ (arr[i]/exp)%n ]++;
// Change count[i] so that count[i] now contains actual
// position of this digit in output[]
for (i = 1; i < n; i++)
count[i] += count[i - 1];
// Build the output array
for (i = n - 1; i >= 0; i--)
{
output[count[ (arr[i]/exp)%n] - 1] = arr[i];
count[(arr[i]/exp)%n]--;
}
// Copy the output array to arr[], so that arr[] now
// contains sorted numbers according to curent 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 sort(int arr[], int n)
{
// Do counting sort for first digit in base n. Note that
// instead of passing digit number, exp (n^0 = 0) is passed.
countSort(arr, n, 1);
// Do counting sort for second digit in base n. Note that
// instead of passing digit number, exp (n^1 = n) is passed.
countSort(arr, n, n);
}
// A utility function to print an array
void printArr(int arr[], int n)
{
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
}
// Driver program to test above functions
int main()
{
// Since array size is 7, elements should be from 0 to 48
int arr[] = {40, 12, 45, 32, 33, 1, 22};
int n = sizeof(arr)/sizeof(arr[0]);
cout << "Given array is \n";
printArr(arr, n);
sort(arr, n);
cout << "\nSorted array is \n";
printArr(arr, n);
return 0;
}
Output:-
Given array is
40 12 45 32 33 1 22
Sorted array is
1 12 22 32 33 40 45
