Puzzle: Sort an array of 0's and 1's in one parse.

Question

Is it possible to arrange the array made up of only 1\'s and 0\'s in descending order within one parse without using auxiliary array?
For example: Suppose you have an ar

Answer 1

Give it a try!

(read comments):

#include
int main(void){
    int a[]={1,0,0,0,1,0,1};
    int n = 7,
        i,
        index = 0;

   while(index < n && a[index]) index++; // skip initial 1's
   for(i = index; i < n; i++){  
     if(a[i]) a[index++] = 1; // if `1` at a[i] make its 0 and
     a[i] = 0;                // make at index 1. 
   }

   for(i = 0; i < n; i++){
        printf("%3d", a[i]);
   }
    return 1;
}

Check working code @ideone's links:

Case-1: {1,0,0,0,1,0,1}
Case-2: {1,0,1,1,1,0,0,1,0,1, 1}
Case-3: {1,1,1,1,1,1,1}
Case-4: {0, 0, 0, 0, 0, 0, 0}
Case-5: {0, 0, 0, 1, 1, 1, 1}

So I think it works correct!
its simple, it need only n iterations.
complexity wise O(n).