P3377 【模板】左偏树（可并堆）

https://www.luogu.com.cn/record/98989138

Luogu/P3377/P3377.cpp

@@ -0,0 +1,136 @@
+#include <iostream>
+#include <memory>
+#include <stack>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+class LeftTree : public std::enable_shared_from_this<LeftTree> {
+  public:
+    using pointer_type = std::shared_ptr<LeftTree>;
+
+  private:
+    size_t dist;
+    pointer_type lchild, rchild;
+    std::weak_ptr<LeftTree> root;
+
+  public:
+    int id, val;
+
+    LeftTree(const int& _val = 0, const int& _id = 0)
+        : dist(0),
+          lchild(nullptr),
+          rchild(nullptr),
+          root(),
+          id(_id),
+          val(_val) {}
+
+    pointer_type find_root() {
+        std::stack<pointer_type> st;
+        pointer_type cur = shared_from_this();
+
+        st.emplace(cur);
+
+        while (auto ptr = cur->root.lock()) {
+            st.emplace(cur = ptr);
+        }
+
+        while (!st.empty()) {
+            auto ptr = st.top();
+            st.pop();
+
+            ptr->root = cur;
+        }
+
+        cur->root.reset();
+
+        return cur;
+    }
+
+    void erase() {
+        if (lchild) lchild->root.reset();
+        if (rchild) rchild->root.reset();
+
+        root = merge(lchild, rchild);
+    }
+
+    static pointer_type merge(pointer_type x, pointer_type y) {
+        if (!x) return y;
+        if (!y) return x;
+
+        if (x->val > y->val || x->val == y->val && x->id > y->id) std::swap(x, y);
+
+        x->rchild = merge(x->rchild, y);
+
+        if (!x->lchild || x->lchild->dist < x->rchild->dist) std::swap(x->lchild, x->rchild);
+
+        if (x->lchild) x->lchild->root = x;
+        if (x->rchild) x->rchild->root = x;
+
+        x->dist = x->rchild ? x->rchild->dist + 1 : 0;
+
+        return x;
+    }
+};
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+
+    cin >> n >> m;
+
+    std::vector<bool> exists(n + 1, true);
+    std::vector<LeftTree::pointer_type> tr(n + 1);
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+
+        tr[i] = std::make_shared<decltype(tr)::value_type::element_type>(x, i);
+    }
+
+    while (m--) {
+        int op;
+
+        cin >> op;
+
+        if (op == 1) {
+            int x, y;
+
+            cin >> x >> y;
+
+            if (exists[x] && exists[y]) {
+                auto fx = tr[x]->find_root(),
+                     fy = tr[y]->find_root();
+
+                if (fx != fy) {
+                    decltype(tr)::value_type::element_type::merge(fx, fy);
+                }
+            }
+        } else {  // op == 2
+            int x;
+
+            cin >> x;
+
+            if (exists[x]) {
+                auto fx = tr[x]->find_root();
+
+                if (exists[fx->id]) {
+                    cout << fx->val << endl;
+
+                    fx->erase();
+                    exists[fx->id] = false;
+                } else {
+                    cout << -1 << endl;
+                }
+            } else {
+                cout << -1 << endl;
+            }
+        }
+    }
+
+    return 0;
+}