#include "railroad.h" #include <bits/stdc++.h> using namespace std; typedef long long ll; const ll INF = 1e18; long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) { int n = (int) s.size(); vector<int> bin; for (int i = 0; i < n; i++) { bin.push_back(s[i]); bin.push_back(t[i]); } sort(bin.begin(),bin.end()); bin.erase(unique(bin.begin(),bin.end()),bin.end()); int K = bin.size(); vector<vector<int>> in(K); vector<int> out(K); for (int i = 0; i < n; i++) { int u = lower_bound(bin.begin(),bin.end(),t[i])-bin.begin(); int v = lower_bound(bin.begin(),bin.end(),s[i])-bin.begin(); assert(u < K && v < K); in[u].push_back(v); out[v]++; } int a = 0, b = 0, c = 0; for (int u = 0; u < K; u++) { int deg = in[u].size() - out[u]; if (deg == 1) a++; else if (deg == -1) b++; else if (deg != 0) c++; } // cout << a << " " << b << " " << c << "\n"; if (a == 1 && b == 1 && c == 0) return 0; // vector<int> res; // while (!st.empty()) { // for (int ) // } return 1; }