Submission #484440

#	Time	Username	Problem	Language	Result	Execution time	Memory
484440		ACmachine	Senior Postmen (BOI14_postmen)	C++17	100 / 100	403 ms	45288 KiB

postmen

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;

typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vi;
typedef vector<ll> vll;

#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define MANY_TESTS int tcase; cin >> tcase; while(tcase--)

const double EPS = 1e-9;
const int MOD = 1e9+7;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};

void DBG(){cout << "]" << endl;}
template<typename T, typename ...U> void DBG(const T& head, const U... args){ cout << head << "; "; DBG(args...); }
#define dbg(...) cout << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__);
#define chk() cout << "Check at line(" << __LINE__ << ") hit." << endl;

template<class T, unsigned int U>
ostream& operator<<(ostream& out, const array<T, U> &v){out << "[";  REP(i, U) out << v[i] << ", ";  out << "]"; return out;}
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "[";  REP(i, v.size()) out << v[i] << ", ";  out << "]"; return out;}

template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());


// returns -2 if doesn't exist, -1 if cycle, else possible starting vertex; doesn't check if connected
int check_eulerian_path(const vector<vector<array<int, 2>>> &g){

}
// g[x] = {y, edge_id}
// m = number of edges in graph;
// returns the edge_ids on the path
vector<int> find_eulerian_path(const vector<vector<array<int, 2>>> &g, int m, int s){
    vector<bool> visited(m, false);
    vector<int> ptr(g.size(), 0);
    vector<array<int, 2>> stk;
    vector<int> tour;
    stk.push_back({s, -1});
    while(!stk.empty()){
        bool found = false;
        int v = stk.back()[0];
        while(ptr[v] < g[v].size()){
            int id = g[v][ptr[v]][1];
            if(visited[id]){
                ptr[v]++; continue;
            }
            stk.push_back({g[v][ptr[v]][0], id});
            visited[id] = true; ptr[v]++;
            found = true;
            break;
        }
        if(!found){
            tour.push_back(stk.back()[1]);
            stk.pop_back();
        }
    }
    tour.pop_back();
    reverse(all(tour));
    return tour;
}

int main(){
 	ios_base::sync_with_stdio(false);
 	cin.tie(NULL); cout.tie(NULL);
 	int n, m;
 	cin >> n >> m;
 	vector<vector<array<int, 2>>> g(n);
 	vector<array<int, 2>> edges;
    REP(i, m){
        int u, v;
        cin >> u >> v;
        u--; v--;
        g[u].pb({v, i});
        g[v].pb({u, i});
        edges.pb({u, v});
    }
    vector<int> tour_tm = find_eulerian_path(g, m, 0);
    vector<int> tour_res; tour_res.pb(0);
    REP(i, tour_tm.size()){
        int id = tour_tm[i];
        auto e = edges[id];
        tour_res.pb(e[0] ^ e[1] ^ tour_res.back());
    }
    vector<bool> is_on_stack(n, false);
    vector<int> st;
    vector<vector<int>> ans;
    REP(i, tour_res.size()){
        if(is_on_stack[tour_res[i]]){
            while(st.back() != tour_res[i]){
                is_on_stack[st.back()] = false;
                cout << st.back() + 1 << " ";
                st.pop_back();

            }
            cout << st.back() + 1 << "\n";
        }
        else{
            st.push_back(tour_res[i]);
            is_on_stack[tour_res[i]] = true;
        }
    }
    return 0;
}

Compilation message (stderr)

postmen.cpp: In function 'int check_eulerian_path(const std::vector<std::vector<std::array<int, 2> > >&)':
postmen.cpp:63:1: warning: no return statement in function returning non-void [-Wreturn-type]
   63 | }
      | ^
postmen.cpp: In function 'std::vector<int> find_eulerian_path(const std::vector<std::vector<std::array<int, 2> > >&, int, int)':
postmen.cpp:76:22: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} and 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |         while(ptr[v] < g[v].size()){
postmen.cpp: In function 'int main()':
postmen.cpp:19:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 | #define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
      |                                        ^
postmen.cpp:21:18: note: in expansion of macro 'FOR'
   21 | #define REP(i,b) FOR(i,0,b,1)
      |                  ^~~
postmen.cpp:113:5: note: in expansion of macro 'REP'
  113 |     REP(i, tour_tm.size()){
      |     ^~~
postmen.cpp:19:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 | #define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
      |                                        ^
postmen.cpp:21:18: note: in expansion of macro 'FOR'
   21 | #define REP(i,b) FOR(i,0,b,1)
      |                  ^~~
postmen.cpp:121:5: note: in expansion of macro 'REP'
  121 |     REP(i, tour_res.size()){
      |     ^~~

• Subtask 1: 38 / 38
• Subtask 2: 17 / 17
• Subtask 3: 45 / 45