Submission #1233184

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233184		goulthen	Senior Postmen (BOI14_postmen)	C++20	100 / 100	327 ms	73524 KiB

postmen

//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T>
using Tree =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
 
#define int long long
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define rep(i, a, b) for (int i = a; i <= b; ++i)
#define per(i, b, a) for (int i = b; i >= a; --i)
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()
#define lsb(x) (x)&(-x)
#define bug(x) cerr << #x << " " << x << endl;
 
void setIO(string name = "") {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    if (!name.empty()) {
        freopen((name + ".in").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
}
 
ll fexp(ll a, ll b, ll m) {
    if (b == 0) return 1LL;
    ll p = a;
    ll ans = 1;
    while (b > 0) {
        if (b % 2 != 0) ans = (ans * p) % m;
        p = (p * p) % m;
        b >>= 1;
    }
    return ans;
}
 
const int MAXN = 5e5 + 10;
const int INF = 1e18 + 5;
const int MOD = 1e9+7;
vector<pii> g[MAXN];
bool mk[MAXN];
int n,m;
vector<int> path;
 
void dfs(int u) {
    while (!g[u].empty()) {
        auto [v,id] = g[u].back();
        g[u].pop_back();
        if (mk[id]) continue;
        mk[id] = 1;
        dfs(v);
    }
    path.pb(u);
}
 
void solve() {
    int n,m;cin >> n >> m;
    rep(i,1,m) {
        int u,v;cin >> u >> v;
        g[u].pb({v,i});
        g[v].pb({u,i});
    }

    dfs(1);
    rep(i,1,n) mk[i] = 0;
    stack<int> ans;
 
    for (auto &x : path) {
        if (mk[x]) {
            while (ans.top() != x) {
                cout << ans.top() << ' ';
                mk[ans.top()] = 0;
                ans.pop();
            }
            cout << x << '\n';
        }else { 
            ans.push(x);
            mk[x] = 1;
        }
    }
}
 
int32_t main() {
    setIO();
    int tt = 1;
    //cin >> tt;
 
    while (tt-- > 0) solve();
    return 0;
}

Compilation message (stderr)

postmen.cpp: In function 'void setIO(std::string)':
postmen.cpp:29:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |         freopen((name + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
postmen.cpp:30:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |         freopen((name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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