diff --git a/Luogu/P2147/P2147.cpp b/Luogu/P2147/P2147.cpp new file mode 100644 index 00000000..7d2aa811 --- /dev/null +++ b/Luogu/P2147/P2147.cpp @@ -0,0 +1,165 @@ +#include +#include +#include + +using std::cin; +using std::cout; +const char endl = '\n'; + +const int N = 1e4 + 5; + +class LinkCutTree { + private: + struct node { + size_t l, r, f; + bool rev; + + node(const size_t &_f = 0) + : l(0), r(0), f(_f), rev(false) {} + + size_t &child(unsigned x) { + return !x ? l : r; + } + } tr[N]; + + inline void pushdown(const size_t &u) { + if (!tr[u].rev) return; + + std::swap(tr[u].l, tr[u].r); + tr[tr[u].l].rev = !tr[tr[u].l].rev; + tr[tr[u].r].rev = !tr[tr[u].r].rev; + tr[u].rev = false; + } + + unsigned relation(const size_t &u) { + return u == tr[tr[u].f].l ? 0 : 1; + } + + bool isRoot(const size_t &u) { + return tr[tr[u].f].l != u && tr[tr[u].f].r != u; + } + + void rotate(size_t u) { + size_t p = tr[u].f; + unsigned x = relation(u); + + if (!isRoot(p)) { + tr[tr[p].f].child(relation(p)) = u; + } + tr[u].f = tr[p].f; + + if (tr[u].child(x ^ 1)) { + tr[tr[u].child(x ^ 1)].f = p; + } + tr[p].child(x) = tr[u].child(x ^ 1); + + tr[u].child(x ^ 1) = p; + tr[p].f = u; + } + + void splay(size_t u) { + std::stack st; + + size_t cur = u; + st.push(cur); + while (!isRoot(cur)) { + st.push(tr[cur].f); + cur = tr[cur].f; + } + + while (!st.empty()) { + pushdown(st.top()); + st.pop(); + } + + while (!isRoot(u)) { + if (isRoot(tr[u].f)) { + rotate(u); + } else if (relation(u) == relation(tr[u].f)) { + rotate(tr[u].f); + rotate(u); + } else { + rotate(u); + rotate(u); + } + } + } + + void access(size_t u) { + for (size_t f = 0; u; u = tr[f = u].f) { + splay(u); + tr[u].r = f; + } + } + + void makeRoot(const size_t &u) { + access(u); + splay(u); + tr[u].rev = !tr[u].rev; + } + + size_t findRoot(size_t u) { + access(u); + splay(u); + + while (tr[u].l) { + u = tr[u].l; + } + + return u; + } + + void split(const size_t &x, const size_t &y) { + makeRoot(x); + access(y); + splay(y); + } + + public: + bool check(int x, int y) { + return findRoot(x) == findRoot(y); + } + + void link(const int &x, const int &y) { + makeRoot(x); + + if (findRoot(y) != x) { + tr[x].f = y; + } + } + + void cut(int x, int y) { + split(x, y); + + if (tr[y].l == x) { + tr[y].l = 0; + tr[x].f = 0; + } + } +} lct; + +int main() { + std::ios::sync_with_stdio(false); + cin.tie(nullptr); + + int n, m; + + cin >> n >> m; + + while (m--) { + std::string op; + int u, v; + + cin >> op >> u >> v; + + if (op == "Connect") { + lct.link(u, v); + } else if (op == "Destroy") { + lct.cut(u, v); + } else { // op == "Query" + cout << (lct.check(u, v) ? "Yes" : "No") << endl; + } + } + + return 0; +}