Submission #677833

#TimeUsernameProblemLanguageResultExecution timeMemory
677833dooompyPipes (BOI13_pipes)C++17
44.07 / 100
143 ms19524 KiB
#include "bits/stdc++.h" using namespace std; void abc() {cout << endl;} template <typename T, typename ...U> void abc(T a, U ...b) { cout << a << ' ', abc(b...); } template <typename T> void printv(T l, T r) { while (l != r) cout << *l << " \n"[++l == r]; } template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) { return o >> a.first >> a.second; } template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) { return o << '(' << a.first << ", " << a.second << ')'; } template <typename T> ostream& operator << (ostream& o, vector<T> a) { bool is = false; for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;} return o << '}'; } #ifdef local #define test(args...) abc("[" + string(#args) + "]", args) #else #define test(args...) void(0) #endif using ll = long long; ll v[100005]; set<int> adj[100005]; ll calc[500005]; int en[500005], out[500005]; bool seen[100005]; bool seen2[100005]; vector<pair<int, int>> ord; void dfs(int cur, int p, int root) { int idx = *adj[cur].begin(); int nxtidx = (en[idx] == cur ? out[idx] : en[idx]); if (nxtidx == p) { idx = *adj[cur].rbegin(); nxtidx = (en[idx] == cur ? out[idx] : en[idx]); } ord.push_back({cur, idx}); if (nxtidx != root) dfs(nxtidx, cur, root); } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); // freopen("test.txt", "r", stdin); // freopen("", "w", stdout); int n, m; cin >> n >> m; if (m > n) { cout << 0 << endl; return 0; } for (int i = 1; i <= n; i++) cin >> v[i]; for (int i = 1; i <= m; i++) { int a, b; cin >> a >> b; en[i] = a, out[i] = b; adj[a].insert(i); adj[b].insert(i); } queue<int> q; for (int i = 1; i <= n; i++) { if (adj[i].size() == 1) { q.push(i); } } while (!q.empty()) { // deg 1 auto cur = q.front(); q.pop(); if (adj[cur].size() == 1) { int idx = *adj[cur].begin(); int nxtidx = (en[idx] == cur ? out[idx] : en[idx]); ll weight = v[cur]; v[nxtidx] -= v[cur]; v[cur] -= v[cur]; adj[cur].erase(idx); adj[nxtidx].erase(idx); if (adj[nxtidx].size() == 1) q.push(nxtidx); } } if (m == n - 1) { for (int i = 1; i <= m; i++) { cout << calc[i] * 2 << "\n"; } return 0; } vector<int> left; for (int i = 1; i <= n; i++) { if (adj[i].size() == 2) left.push_back(i); } if (left.size() % 2 == 0) { cout << 0 << endl; return 0; } if (left.empty()) { // wtf cout << 0 << endl; return 0; } int start = left.front(); dfs(left.front(), -1, left.front()); // assert(ord.size() == left.size()); // for (auto x : ord) cout << x << " "; ll prev = 0; for (int i = 0; i < ord.size() - 1; i++) { // assum back ->0 is X prev = v[ord[i].first] - prev; } ll x = (v[ord[0].first] - prev) / 2; // cout << x << endl; calc[ord[0].second] = x; for (int i = 1; i < ord.size(); i++) { calc[ord[i].second] = v[ord[i].first] - calc[ord[i-1].second]; } for (int i = 1; i <= m; i++) { cout << calc[i] * 2 << "\n"; } }

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:96:16: warning: unused variable 'weight' [-Wunused-variable]
   96 |             ll weight = v[cur];
      |                ^~~~~~
pipes.cpp:142:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  142 |     for (int i = 0; i < ord.size() - 1; i++) {
      |                     ~~^~~~~~~~~~~~~~~~
pipes.cpp:155:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  155 |     for (int i = 1; i < ord.size(); i++) {
      |                     ~~^~~~~~~~~~~~
pipes.cpp:132:9: warning: unused variable 'start' [-Wunused-variable]
  132 |     int start = left.front();
      |         ^~~~~
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