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Submission #995754

# Submission time Handle Problem Language Result Execution time Memory
995754 2024-06-09T21:13:31 Z MilosMilutinovic Pipes (BOI13_pipes) C++14
100 / 100
 93 ms 19524 KB 
#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<long long> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<vector<array<int, 2>>> g(n);
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back({y, i});
    g[y].push_back({x, i});
  }
  if (m > n) {
    cout << 0 << '\n';
    return 0;
  }
  if (n == 1) {
    cout << 2 * a[0] << '\n';
    return 0;
  }
  if (m < n) {
    vector<long long> res(m);
    function<void(int, int)> Dfs = [&](int v, int pv) {
      for (auto& e : g[v]) {
        int u = e[0];
        if (u == pv) {
          continue;
        }
        Dfs(u, v);
        if (a[u] != 0) {
          res[e[1]] = 2 * a[u];
          a[v] -= a[u];
        }
      }
    };
    Dfs(0, 0);
    if (a[0] != 0) {
      cout << 0 << '\n';
      return 0;
    }
    for (int i = 0; i < m; i++) {
      cout << res[i] << '\n';
    }
    return 0;
  }
  vector<int> deg(n);
  for (int i = 0; i < n; i++) {
    deg[i] = (int) g[i].size();
  }
  vector<int> que;
  for (int i = 0; i < n; i++) {
    if (deg[i] == 1) {
      que.push_back(i);
    }
  }
  auto orig = a;
  vector<long long> res(m);
  for (int b = 0; b < (int) que.size(); b++) {
    int i = que[b];
    for (auto& e : g[i]) {
      int j = e[0];
      deg[j] -= 1;
      if (deg[j] == 1) {
        que.push_back(j);
      }
    }
  }
  vector<int> where(n);
  for (int b = 0; b < (int) que.size(); b++) {
    where[que[b]] = b;
  }
  for (int b = 0; b < (int) que.size(); b++) {
    int i = que[b];
    for (auto& e : g[i]) {
      int j = e[0];
      if (where[i] < where[j]) {
        res[e[1]] = 2 * a[i];
        a[j] -= a[i];
        a[i] = 0;
      }
    }
  }
  vector<int> cyc;
  for (int i = 0; i < n; i++) {
    if (deg[i] > 1) {
      cyc.push_back(i);
    }
  }
  for (int i : cyc) {
    for (auto& e : g[i]) {
      int j = e[0];
      if (deg[j] < 2) {
        res[e[1]] = 2 * a[j];
        a[i] -= a[j];
        a[j] = 0;
      }
    }
  }
  if ((int) cyc.size() % 2 == 0) {
    cout << 0 << '\n';
    return 0;
  }
  vector<bool> was(n);
  vector<long long> vals;
  vector<int> ids;
  function<void(int)> Dfs = [&](int v) {
    was[v] = true;
    vals.push_back(a[v]);
    int back = -1;
    bool found = false;
    for (auto& e : g[v]) {
      int u = e[0];
      int i = e[1];
      if (u == cyc[0]) {
        back = i;
      }
      if (was[u] || deg[u] <= 1) {
        continue;
      }
      found = true;
      ids.push_back(i);
      Dfs(u);
    }
    if (!found) {
      ids.push_back(back);
    }
  }; 
  Dfs(cyc[0]);
  long long total = 0;
  for (int i = 0; i < (int) vals.size(); i++) {
    total = vals[i] - total;
  }
  if (total % 2 == 1) {
    cout << 0 << '\n';
    return 0;
  }
  total /= 2;
  res[ids.back()] = 2 * total;
  for (int i = 0; i < n; i++) {
    for (auto& p : g[i]) {
      if (p[1] == ids.back()) {
        a[i] -= total;
      }
    }
  }
  was = vector<bool>(n, false);
  Dfs = [&](int v) {
    was[v] = true;
    for (auto& p : g[v]) {
      int u = p[0];
      int i = p[1];
      if (deg[u] <= 1 || was[u] || i == ids.back()) {
        continue;
      }
      Dfs(u);
      res[i] = 2 * a[u];
      a[v] -= a[u];
      a[u] = 0;
    }
  };
  Dfs(cyc.back());
  a = orig;
  for (int i = 0; i < n; i++) {
    long long sum = 0;
    for (auto& p : g[i]) {
      sum += res[p[1]] / 2;
    }
    if (sum != a[i]) {
      cout << 0 << '\n';
      return 0;
    }
  }
  for (int i = 0; i < m; i++) {
    cout << res[i] << '\n';
  }
  return 0;
}

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 32 ms 8276 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 27 ms 6708 KB Output is correct
14 Correct 33 ms 8016 KB Output is correct
15 Correct 34 ms 8532 KB Output is correct
16 Correct 30 ms 7248 KB Output is correct
17 Correct 32 ms 8280 KB Output is correct
18 Correct 34 ms 8532 KB Output is correct
19 Correct 36 ms 12368 KB Output is correct
20 Correct 0 ms 344 KB Output is correct
21 Correct 1 ms 348 KB Output is correct
22 Correct 36 ms 8352 KB Output is correct
23 Correct 28 ms 6740 KB Output is correct
24 Correct 36 ms 8532 KB Output is correct
25 Correct 28 ms 7004 KB Output is correct

Subtask #2
70.0 / 70.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 604 KB Output is correct
3 Correct 29 ms 9432 KB Output is correct
4 Correct 26 ms 6740 KB Output is correct
5 Correct 24 ms 6916 KB Output is correct
6 Correct 93 ms 17232 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 448 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 1 ms 600 KB Output is correct
16 Correct 1 ms 348 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 1 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 0 ms 348 KB Output is correct
21 Correct 1 ms 348 KB Output is correct
22 Correct 0 ms 348 KB Output is correct
23 Correct 40 ms 14056 KB Output is correct
24 Correct 48 ms 15800 KB Output is correct
25 Correct 31 ms 9428 KB Output is correct
26 Correct 29 ms 6740 KB Output is correct
27 Correct 24 ms 6492 KB Output is correct
28 Correct 28 ms 7000 KB Output is correct
29 Correct 76 ms 14676 KB Output is correct
30 Correct 42 ms 14668 KB Output is correct
31 Correct 44 ms 19524 KB Output is correct
32 Correct 39 ms 12200 KB Output is correct
33 Correct 28 ms 9808 KB Output is correct
34 Correct 22 ms 6748 KB Output is correct
35 Correct 23 ms 6748 KB Output is correct
36 Correct 24 ms 7004 KB Output is correct
37 Correct 93 ms 17236 KB Output is correct
38 Correct 43 ms 15180 KB Output is correct
39 Correct 38 ms 11464 KB Output is correct
40 Correct 46 ms 15464 KB Output is correct
41 Correct 27 ms 9688 KB Output is correct
42 Correct 25 ms 6748 KB Output is correct
43 Correct 25 ms 6536 KB Output is correct
44 Correct 25 ms 7000 KB Output is correct
45 Correct 77 ms 14256 KB Output is correct
46 Correct 42 ms 14412 KB Output is correct
47 Correct 42 ms 15692 KB Output is correct
48 Correct 47 ms 19400 KB Output is correct
49 Correct 28 ms 9428 KB Output is correct
50 Correct 24 ms 6736 KB Output is correct
51 Correct 23 ms 7004 KB Output is correct
52 Correct 22 ms 6740 KB Output is correct
53 Correct 74 ms 14420 KB Output is correct
54 Correct 44 ms 13904 KB Output is correct