Submission #656492

#	Time	Username	Problem	Language	Result	Execution time	Memory
656492		600Mihnea	Senior Postmen (BOI14_postmen)	C++17	100 / 100	405 ms	75488 KiB

postmen

bool home = 0;
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 500000 + 7;
int n;
int m;
int sum[N];
bool vis[N];
vector<int> g[N];
vector<int> ord;

void go(int a) {
  while (!g[a].empty()) {
    int i = g[a].back();
    g[a].pop_back();
    if (vis[i]) {
      continue;
    }
    vis[i] = 1;
    go(sum[i] - a);
    ord.push_back(a);
  }
}

signed main() {
  if (home == 0) {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  } else {
    freopen ("___input___.txt", "r", stdin);
  }

  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int a, b;
    cin >> a >> b;
    sum[i] = a + b;
    g[a].push_back(i);
    g[b].push_back(i);
  }
  go(1);
  for (int i = 1; i <= m; i++) {
    assert(vis[i]);
  }
  for (int i = 1; i <= n; i++) {
    vis[i] = 0;
  }
  assert((int) ord.size() == m);
  assert(!ord.empty());
  ord.push_back(ord[0]);

  vector<int> stk;
  for (auto &x : ord) {
    if (vis[x] == 0) {
      stk.push_back(x);
      vis[x] = 1;
      continue;
    }
    cout << x << " ";
    while (stk.back() != x) {
      cout << stk.back() << " ";
      vis[stk.back()] = 0;
      stk.pop_back();
    }
    cout << "\n";
  }
  return 0;
  while ((int) ord.size() > 1) {
    int dim = (int) ord.size();
    set<int> s;
    for (int r = 0; r < dim; r++) {
      int x = ord[r];
      if (s.count(x)) {
        s.clear();
        int l = r;
        s.insert(ord[l]);
        while (!s.count(ord[l - 1])) {
          l--;
          s.insert(ord[l]);
        }
        vector<int> new_ord, now;
        for (int j = 0; j < dim; j++) {
          if (l <= j && j <= r) {
            now.push_back(ord[j]);
            continue;
          }
          new_ord.push_back(ord[j]);
        }
        for (auto &v : now) {
          cout << v << " ";
        }
        cout << "\n";
        ord = new_ord;
        break;
      } else {
        s.insert(x);
      }
    }
  }
  if (0) {
    cout << " ---> ";
    for (auto &x : ord) {
      cout << x << " ";
    }
    cout << "\n";
  }

  return 0;
}

Compilation message (stderr)

postmen.cpp: In function 'int main()':
postmen.cpp:33:13: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     freopen ("___input___.txt", "r", stdin);
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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