LISTING 1

	
#include <stdio.h>

#define NULL_IDX 0

typedef struct {
	char value;
	size_t left_child;
	size_t right_child;
} Node;

static Node tree[] = {
	{' ',  NULL_IDX, NULL_IDX},	/* [0] */
	{'*',        2,        3},	/* [1] */
	{'+',        4,        5},	/* [2] */
	{'-',        6,        7},	/* [3] */
	{'A', NULL_IDX, NULL_IDX},	/* [4] */
	{'B', NULL_IDX, NULL_IDX},	/* [5] */
	{'C', NULL_IDX, NULL_IDX},	/* [6] */
	{'/',        8,        9},	/* [7] */
	{'D', NULL_IDX, NULL_IDX},	/* [8] */
	{'E', NULL_IDX, NULL_IDX}	/* [9] */
};

static size_t root = 1;

