binary_tree_using_array.c

#include <stdio.h>
int complete_node = 15;
char tree[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', '\0', '\0', 'J', '\0', 'K', 'L'};

int get_right_child(int index){
    if(tree[index]!='\0' && ((2*index)+2)<=complete_node)
        return (2*index)+2;
    return -1;
}

int get_left_child(int index){
    if(tree[index]!='\0' && (2*index+1)<=complete_node)
        return 2*index+1;
    return -1;
}

void preorder(int index){
    if(index>=0 && tree[index]!='\0'){
        printf(" %c ",tree[index]); 
        preorder(get_left_child(index));
        preorder(get_right_child(index)); 
    }
}

void postorder(int index){
    if(index>=0 && tree[index]!='\0'){
        postorder(get_left_child(index)); 
        postorder(get_right_child(index)); 
        printf(" %c ",tree[index]); 
    }
}

void inorder(int index){
    if(index>=0 && tree[index]!='\0'){
        inorder(get_left_child(index));
        printf(" %c ",tree[index]); 
        inorder(get_right_child(index)); 
    }
}

int main(){
    printf("Preorder:\n");
    preorder(0);
    printf("\nPostorder:\n");
    postorder(0);
    printf("\nInorder:\n");
    inorder(0);
    printf("\n");
    return 0;
}