typedef struct treap_node_t treap_node_t;
struct treap_node_t {
    /* left child */
    treap_node_t *left;
    /* right child */
    treap_node_t *right;

    /* priority that will be randomly set at insertion */
    int priority;

    /* the key of the node which will also be used for sorting */
    void *key;
};

typedef struct treap_t treap_t;
struct treap_t {
    /* root of the tree */
    treap_node_t *root;

    /* function used for comparing the keys */
    int (*cmp)(const void *key1, const void *key2);
};