radix_sort.c

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; 
} 
void countSort(int arr[], int n, int exp) 
{ 
	int output[n]; // output array 
	int i, count[10] = {0}; 
	for (i = 0; i < n; i++) 
		count[ (arr[i]/exp)%10 ]++; 
	for (i = 1; i < 10; i++) 
		count[i] += count[i - 1]; 
	for (i = n - 1; i >= 0; i--) 
	{ 
		output[count[ (arr[i]/exp)%10 ] - 1] = arr[i]; 
		count[ (arr[i]/exp)%10 ]--; 
	} 
	for (i = 0; i < n; i++) 
		arr[i] = output[i]; 
} 

void radixsort(int arr[], int n) 
{ 
	int m = getMax(arr, n); 
	for (int exp = 1; m/exp > 0; exp *= 10) 
		countSort(arr, n, exp); 
} 

int main() 
{ 
	int arr[] = {170, 45, 75, 90, 802, 24, 2, 66}; 
	int n = sizeof(arr)/sizeof(arr[0]); 
	radixsort(arr, n); 
	return 0; 
}