Submission #1119669

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119669		vjudge1	Senior Postmen (BOI14_postmen)	C++17	55 / 100	520 ms	70712 KiB

postmen

#include<bits/stdc++.h>
#define ii pair<int,int>
#define fi first
#define se second
#define int long long
#define task ""
using namespace std;

const int N = 5e5 + 10, mod = 1e9 + 7;
const int oo = 1e18;
int n, m;

struct edge{
    int v, id;
};
vector<edge> g[N];
bool used_edge[N], vst[N];
stack<int> st;

list<int> euler_walk(int u){
    list<int> ans;
    ans.push_back(u);
    while(!g[u].empty()){
        int v = g[u].back().v;
        int id = g[u].back().id;
        g[u].pop_back();

        if(used_edge[id]) continue;
        used_edge[id] = 1;
        u = v;
        ans.push_back(u);
    }
    for(auto it = ++ans.begin(); it != ans.end(); it++){
        auto t = euler_walk(*it);

        t.pop_back();
        ans.splice(it, t);
    }
    return ans;
}
main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if(fopen(task ".inp", "r")){
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    cin >> n >> m;
    for(int i = 1; i <= m; i++){
        int u, v; cin >> u >> v;
        g[u].push_back({v, i});
        g[v].push_back({u, i});
    }
    list<int> ans = euler_walk(1);
    vector<int> v;
    for(int x : ans) v.push_back(x);
//    v.pop_back();
//    for(int i = 0; i < v.size(); i++)
//        cout << v[i] << ' ';
//    cout << '\n';
    for(int i = 0; i < v.size(); i++){
//        cout << v[i] << ' ';
        if(vst[v[i]]){
            int x = st.top();
            cout << v[i] << ' ';
            while(x != v[i]){
                cout << x << ' ';
                vst[x] = 0;
                st.pop();
                x = st.top();
            }
            st.pop();
            cout << '\n';
        }
        st.push(v[i]);
        vst[v[i]] = 1;
    }
}

Compilation message (stderr)

postmen.cpp:41:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   41 | main(){
      | ^~~~
postmen.cpp: In function 'int main()':
postmen.cpp:60:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     for(int i = 0; i < v.size(); i++){
      |                    ~~^~~~~~~~~~
postmen.cpp:44:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
postmen.cpp:45:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 38 / 38
• Subtask 2: 17 / 17
• Subtask 3: 0 / 45