#include <stdio.h>
#include <math.h> // give compiler the "-lm" option


#define PARENT(i) ((i-1) / 2)
#define LINE_WIDTH 110 // use wider line to wider tree
#define NUM_NODES 31 // number of nodes to draw
int tree[NUM_NODES]={0,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6}; // nodes to draw

void print_tree()
{
    int print_pos[NUM_NODES];
    int i, j, k, pos, x=1, level=0;

    print_pos[0] = 0;
    for(i=0,j=1; i<NUM_NODES; i++,j++) {
        pos = print_pos[PARENT(i)] + (i%2?-1:1)*(LINE_WIDTH/(pow(2,level+1))+1);

        for (k=0; k<pos-x; k++) printf("%c",i==0||i%2?' ':'-');
        printf("%d",tree[i]);

        print_pos[i] = x = pos+1;
        if (j==pow(2,level)) {
            printf("\n");
            level++;
            x = 1;
            j = 0;
        }
    }
}



int main()
{
 print_tree();
 return 0;
}