Tree DS implementation in C language

Tree.c

int main(){
    node * root = NULL;
    int a[100005],K,i = 0,j = 0, _element, present;
    
    scanf("%d",&K);
    for( j = 0; j < K;j++ ) {
        scanf("%d",&a[i++]);    
    }

    for( i = 0; i < K;i++ ){
        root = addElement(root,a[i]);
    }
    
    int q;
    scanf("%d", &q);
    
    while (q--) {
        scanf("%d",&_element);
        present = isPresent(root, _element);
        printf("%d\n", present);
    }
    
    return 0;
}
node * addElement(node * root, int x ){
    if( root == NULL ) {
        root = (node *) (malloc(sizeof(node))); 
        root->val = x;root->val1 = -1;
                            root->left = NULL; root->right = NULL;
        return root;
    }
    if( x < root->val ) {
         root->left = addElement(root->left,x);
    }
    else {
        root->right = addElement(root->right,x);                            
    }
    return root;
}

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define max( a, b ) ( ((a) > (b)) ? (a) : (b) )
struct node {
    struct node *left,*right;
    int val, val1;
};
typedef struct node node;
node * addElement(node * root, int x);

/* Any extra functions you would like to add, code here */

int isPresent(node* root, int val){
    /* For your reference
       struct node {
        struct node *left,*right;
        int val;
    };
    */
}