distinctsort.c

/*
 Karan Chawla
 Algorithm: Sort distinct integers in a given array
*/

#include <stdio.h>
#include <stdlib.h> 

//utlitiy function used by qsort
int comp (const void * elem1, const void * elem2) 
{
    int f = *((int*)elem1);
    int s = *((int*)elem2);
    if (f > s) return  1;
    if (f < s) return -1;
    return 0;
}

//utility function to find maximum
int findMax(int *a, int size){
	int max = -1;
	for (int i=0;i<size;i++){
		if(a[i]>max){
			max = a[i];
		}
	}
	return max;
}

//utility function to count occurences of each digit
void count(int *a, int size, int e, int *output){
	int i;
	int count[10]={0};

	for(int i=0;i<size;i++){
		count[(a[i]/e)%10]++;
	}
	
	for(int i=0;i<10;i++) {
		if(count[i]>0){
			output[i] = i;
		}
	}
}

//Driver function
int main(void){
	int temp[] = {131, 20, 11, 455};
	int size = sizeof(temp)/sizeof(*temp);
	int output[10];

	for(int i=0;i<10;i++) output[i] = -1;
	int max = findMax(temp,size);

	for(int e=1; max/e > 0; e*=10){
		count(temp, size, e, output);
	}
	
	qsort (output, 10, sizeof(*output), comp);
	for(int i=1;i<10;i++){
		if (output[i]>-1)
			printf("%d ", output[i]); 
	}
	return 0;
}