Create priority_queue.cpp

data_structure/queue/priority_queue.cpp

@@ -0,0 +1,106 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+template<typename T>
+class pq {
+private:
+    int size, height;
+    struct Node {
+        T value;
+        Node *l, *r, *parent;
+        Node(T val) : value(val), l(nullptr), r(nullptr), parent(nullptr) {} // Node constructor
+    };
+    Node* root;
+
+public:
+    pq() : root(nullptr), size(0), height(0) {}
+
+    void insert(T value) {
+        size++;
+        if ((size & (size - 1)) == 0) height++;
+        if (size == 1) {
+            root = new Node(value);
+            return;
+        }
+
+        Node* now = root;
+        for (int i = height - 2; i >= 0; i--) {
+            if (((1 << i) & size) == 0) {
+                if (!now->l) now->l = new Node(0);
+                now->l->parent = now;
+                now = now->l;
+            } else {
+                if (!now->r) now->r = new Node(0);
+                now->r->parent = now;
+                now = now->r;
+            }
+        }
+        now->value = value;
+
+        while (now->parent && now->value < now->parent->value) {
+            swap(now->value, now->parent->value);
+            now = now->parent;
+        }
+    }
+
+    void pop() {
+        if (size == 0) return;
+        Node* now = root;
+
+        for (int i = height - 2; i >= 0; i--) {
+            if (((1 << i) & size) == 0) {
+                now = now->l;
+            } else {
+                now = now->r;
+            }
+        }
+
+        if (size > 1) {
+            swap(root->value, now->value);
+        }
+
+        if (now->parent) {
+            if (now == now->parent->l) now->parent->l = nullptr;
+            else now->parent->r = nullptr;
+        }
+        delete now;
+
+        if ((size & (size - 1)) == 0) height--;
+        size--;
+
+        now = root;
+        while (now && (now->l || now->r)) {
+            Node* smallest = now;
+            if (now->l && now->l->value < smallest->value) smallest = now->l;
+            if (now->r && now->r->value < smallest->value) smallest = now->r;
+            if (smallest == now) break;
+            swap(now->value, smallest->value);
+            now = smallest;
+        }
+    }
+
+    T top() {
+        return root->value;
+    }
+
+    bool empty() const{
+        return size == 0;
+    }
+};
+
+int main() {
+    cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(false);
+    pq<int> test;
+    int n; cin >> n;
+    while (n--){
+        int x; cin >> x;
+        if (x) test.insert(x);
+        else{
+            if (test.empty())   cout << 0 << "\n";
+            else {
+                cout << test.top() << "\n"; test.pop();
+            }
+        }
+    }
+    return 0;
+}