Teap树堆

Treap

#include<cstdio>
#include<cmath>
#include<cstdlib>

using namespace std;

struct _node
{
struct _node * left;
struct _node * right;
int key;
int priority;
_node(int k):left(NULL), right(NULL), key(k), priority(rand()){};
};

//左旋
void leftRotate(struct _node *& a)
{
struct _node * b = a->right;
a->right = b->left;
b->left = a;
a = b;
}

//右旋
void rightRotate(struct _node *& a)
{
struct _node * b = a->left;
a->left = b->right;
b->right = a;
a = b;
}

//插入
void insert(struct _node *& root, int key)
{
if(!root)
{
root = new _node(key);
return;
}
if(key < root->key)
{
insert(root->left, key);
if(root->priority > root->left->priority)
rightRotate(root);
}
else
{
insert(root->right, key);
if(root->priority > root->right->priority)
leftRotate(root);
}
}

//查询
int query(struct _node * root, int key)
{
struct _node * p = root;
int res = 0;
while(p)
{
if(p->key == key) return key;
else if(p->key < key)
{
res = p->key;
p = p->right;
}
else
p = p->left;
}
return res;
}

int main(void)
{
int n,c,k;
scanf("%d",&n);
struct _node * root = NULL;
while(n--)
{
scanf("%c%c%d", &c,&c,&k);
if(c == 'I')
insert(root, k);
else
printf("%d\n", query(root, k));
}
return 0;
}