ALG Problem N1 (Version 2)

#include <stdlib.h>
#include <vector>

using namespace std;

struct node {
    node* left;
    node* right;
    int value;
    node(int _v = 0) {
        left = NULL;
        right = NULL;
        value = 0;
        value = _v;
    }
}

int n, a[3030];

void add(node* i, int v) {
    if (v < i->value) {
        if (i->left == NULL)
            i->left = new node(v);
        else
            add(i->left, v);
    } else {
        if (i->right == NULL)
            i->right = new node(v);
        else
            add(i->right, v);
    }
}

void dfs(node* i) {
    if (i == NULL)
        return;
    dfs(i->right);
    dfs(i->left);
    printf("%i ", i->value);
}

int main()
{
    scanf("%i", &n);
    for (int i = 0; i < n; i++)
        scanf("%i", &a[i]);
    node* root = new node(a[n-1]);
    for (int i = n-1; i >= 0; i--)
        add(root, a[i]);

    dfs(root);
    system("PAUSE");
    return 0;
}