treap cp algorithms code example
Example: treap cp algorithms
struct item {
int key, prior;
item * l, * r;
item() { }
item (int key, int prior) : key(key), prior(prior), l(NULL), r(NULL) { }
};
typedef item * pitem;
void split (pitem t, int key, pitem & l, pitem & r) {
if (!t)
l = r = NULL;
else if (key < t->key)
split (t->l, key, l, t->l), r = t;
else
split (t->r, key, t->r, r), l = t;
}
void insert (pitem & t, pitem it) {
if (!t)
t = it;
else if (it->prior > t->prior)
split (t, it->key, it->l, it->r), t = it;
else
insert (it->key < t->key ? t->l : t->r, it);
}
void merge (pitem & t, pitem l, pitem r) {
if (!l || !r)
t = l ? l : r;
else if (l->prior > r->prior)
merge (l->r, l->r, r), t = l;
else
merge (r->l, l, r->l), t = r;
}
void erase (pitem & t, int key) {
if (t->key == key) {
pitem th = t;
merge (t, t->l, t->r);
delete th;
}
else
erase (key < t->key ? t->l : t->r, key);
}
pitem unite (pitem l, pitem r) {
if (!l || !r) return l ? l : r;
if (l->prior < r->prior) swap (l, r);
pitem lt, rt;
split (r, l->key, lt, rt);
l->l = unite (l->l, lt);
l->r = unite (l->r, rt);
return l;
}