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P1168.cc
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P1168.cc
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#include <cstdio>
#include <cstdlib>
class SBT {
public:
void insert(int key);
int select(int rank);
SBT() : tree_(NULL) {
}
~SBT() {
deleteTree(tree_);
}
private:
typedef struct TNode {
int key;
size_t size;
struct TNode *left, *right;
TNode(int key) : key(key), size(1), left(NULL), right(NULL) {}
} *Tree;
size_t getSize(Tree tree) { return tree ? tree->size : 0; }
Tree leftRotate(Tree tree);
Tree rightRotate(Tree tree);
Tree maintain(Tree tree);
Tree maintainLeft(Tree tree);
Tree maintainRight(Tree tree);
Tree insert(Tree tree, int key);
int select(Tree tree, int rank);
void deleteTree(Tree tree);
private:
Tree tree_;
};
void SBT::insert(int key) {
tree_ = insert(tree_, key);
}
int SBT::select(int rank) {
return select(tree_, rank);
}
SBT::Tree SBT::leftRotate(Tree tree) {
Tree k = tree->right;
tree->right = k->left;
k->left = tree;
tree->size = getSize(tree->left) + getSize(tree->right) + 1;
k->size = tree->size + getSize(k->right) + 1;
return k;
}
SBT::Tree SBT::rightRotate(Tree tree) {
Tree k = tree->left;
tree->left = k->right;
k->right = tree;
tree->size = getSize(tree->left) + getSize(tree->right) + 1;
k->size = getSize(k->left) + tree->size + 1;
return k;
}
SBT::Tree SBT::maintain(Tree tree) {
tree = maintainLeft(tree);
return maintainRight(tree);
}
SBT::Tree SBT::maintainLeft(Tree tree) {
if (tree == NULL || tree->left == NULL) return tree;
if (tree->left->left && tree->left->left->size > getSize(tree->right)) {
tree = rightRotate(tree);
tree->right = maintain(tree->right);
tree = maintain(tree);
}
if (tree->left->right && tree->left->right->size > getSize(tree->right)) {
tree->left = leftRotate(tree->left);
tree = rightRotate(tree);
tree->left = maintain(tree->left);
tree->right = maintain(tree->right);
tree = maintain(tree);
}
return tree;
}
SBT::Tree SBT::maintainRight(Tree tree) {
if (tree == NULL || tree->right == NULL) return tree;
if (tree->right->right && tree->right->right->size > getSize(tree->left)) {
tree = leftRotate(tree);
tree->left = maintain(tree->left);
tree = maintain(tree);
}
if (tree->right->left && tree->right->left->size > getSize(tree->left)) {
tree->right = rightRotate(tree->right);
tree = leftRotate(tree);
tree->left = maintain(tree->left);
tree->right = maintain(tree->right);
tree = maintain(tree);
}
return tree;
}
SBT::Tree SBT::insert(Tree tree, int key) {
if (tree == NULL) {
return new TNode(key);
}
tree->size++;
if (key < tree->key) {
tree->left = insert(tree->left, key);
tree = maintainLeft(tree);
}
else {
tree->right = insert(tree->right, key);
tree = maintainRight(tree);
}
return tree;
}
int SBT::select(Tree tree, int rank) {
size_t left_size = getSize(tree->left);
if (rank == left_size) {
return tree->key;
}
else if (rank < left_size) {
return select(tree->left, rank);
}
else {
return select(tree->right, rank - left_size - 1);
}
}
void SBT::deleteTree(Tree tree) {
if (tree == NULL) return;
if (tree->left) deleteTree(tree->left);
if (tree->right) deleteTree(tree->right);
delete tree;
}
int main() {
int n, key;
SBT sbt;
scanf("%d", &n);
for (int i = 1; i <= n; i++) {
scanf("%d", &key);
sbt.insert(key);
if (i % 2) {
printf("%d\n", sbt.select(i / 2));
}
}
return 0;
}