#include <bits/stdc++.h> using namespace std; #define int long long struct Edge { int v, id; }; signed main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n; if (!(cin >> n)) return 0; vector<int> x(n), y(n); for (int i = 0; i < n; ++i) cin >> x[i] >> y[i]; // compress coordinates vector<int> xs = x, ys = y; sort(xs.begin(), xs.end()); xs.erase(unique(xs.begin(), xs.end()), xs.end()); sort(ys.begin(), ys.end()); ys.erase(unique(ys.begin(), ys.end()), ys.end()); int nx = (int)xs.size(); int ny = (int)ys.size(); int V = nx + ny; vector<int> cx(n), cy(n); for (int i = 0; i < n; ++i) { cx[i] = int(lower_bound(xs.begin(), xs.end(), x[i]) - xs.begin()); cy[i] = int(lower_bound(ys.begin(), ys.end(), y[i]) - ys.begin()) + nx; } // adjacency vector<vector<Edge>> g(V); for (int i = 0; i < n; ++i) { g[cx[i]].push_back({cy[i], i}); g[cy[i]].push_back({cx[i], i}); } // arrays sized properly vector<int> vis(V, 0); vector<int> par_edge(V, -1); // par_edge[node] = edge id used to reach node in DFS tree vector<int> used(n, 0); vector<int> deg(V, 0); // ITERATIVE DFS1 to build spanning forest and par_edge for (int start = 0; start < V; ++start) { if (vis[start]) continue; // stack of nodes for DFS stack<int> st; st.push(start); vis[start] = 1; par_edge[start] = -1; while (!st.empty()) { int u = st.top(); st.pop(); for (const Edge &e : g[u]) { int v = e.v; if (vis[v]) continue; vis[v] = 1; par_edge[v] = e.id; // edge id that connects v with its parent u st.push(v); } } } // Select cycle edges (edges that are not par_edge[any endpoint]) for (int i = 0; i < n; ++i) { int u = cx[i], v = cy[i]; if (par_edge[u] != i && par_edge[v] != i) { // non-tree edge if (deg[u] < 2 && deg[v] < 2) { used[i] = 1; deg[u]++; deg[v]++; } } } // Prepare children lists for tree edges so we can get a postorder deterministically vector<vector<pair<int,int>>> children(V); // children[u] = list of (child, edge_id) for (int u = 0; u < V; ++u) { for (const Edge &e : g[u]) { int v = e.v; if (par_edge[v] == e.id) { // e.id is the tree-edge that reaches v from u (u is parent of v) children[u].push_back({v, e.id}); } } } // Iterative postorder traversal using explicit stack (no recursion) vector<int> visited2(V, 0); vector<int> postorder_nodes; // store nodes in postorder for (int root = 0; root < V; ++root) { if (visited2[root]) continue; // stack of pairs (node, state) where state==0 means first time, state==1 means children processed vector<pair<int,int>> st; st.emplace_back(root, 0); while (!st.empty()) { auto [u, state] = st.back(); st.pop_back(); if (state == 0) { if (visited2[u]) continue; visited2[u] = 1; st.emplace_back(u, 1); // will add to postorder after children // push children for (auto &p : children[u]) { int v = p.first; if (!visited2[v]) st.emplace_back(v, 0); } } else { postorder_nodes.push_back(u); } } } // Process edges in postorder: when we process node u, we will visit its children and handle edge (u->child) // We need mapping from child->edge id; children[u] has that. // Because postorder_nodes is nodes (parents after children), we iterate parents in that order for (int u : postorder_nodes) { for (auto &p : children[u]) { int v = p.first; int eid = p.second; if (!used[eid] && deg[u] < 2 && deg[v] < 2) { used[eid] = 1; deg[u]++; deg[v]++; } } } // Output for (int i = 0; i < n; ++i) cout << used[i]; cout << '\n'; return 0; }

Main.cpp: In function 'int main()':
Main.cpp:4:13: error: expected primary-expression before 'long'
    4 | #define int long long
      |             ^~~~
Main.cpp:32:17: note: in expansion of macro 'int'
   32 |         cx[i] = int(lower_bound(xs.begin(), xs.end(), x[i]) - xs.begin());
      |                 ^~~
Main.cpp:4:13: error: expected primary-expression before 'long'
    4 | #define int long long
      |             ^~~~
Main.cpp:33:17: note: in expansion of macro 'int'
   33 |         cy[i] = int(lower_bound(ys.begin(), ys.end(), y[i]) - ys.begin()) + nx;
      |                 ^~~