Submission #782894

#	Time	Username	Problem	Language	Result	Execution time	Memory
782894		makanhulia	The Xana coup (BOI21_xanadu)	C++17	0 / 100	1078 ms	524288 KiB

xanadu

#include<bits/stdc++.h>
#define int long long
using namespace std;
const int MAX=1e9;
int n;
vector<vector<int>> adj;
int cnt(int qu, int u, vector<int> c, int vis) {
  if(qu==n+1) return MAX; int sum=0;
  for(int p : c) sum+=p; if(sum==0) return 0;
  c[u]^=1;
  for(int p : adj[u]) c[p]^=1;
  int ret=MAX;
  for(int i=0; i<n; i++) {
    if(vis&(1 << i)) continue;
    ret=min(ret, 1+cnt(qu+1, i, c, vis^(1LL << i)));
  }
  return ret;
}
signed main() {
  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  cin >> n;
  adj.resize(n);
  for(int i=1; i<n; i++) {
    int u, v; cin >> u >> v; --u; --v;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  vector<int> c(n);
  for(int &p : c) cin >> p;
  int ans=MAX;
  for(int i=0; i<n; i++) {
    ans=min(ans, cnt(1, i, c, (1LL << i)));
  }
  if(ans>=MAX) cout << "impossible\n";
  else cout << ans << '\n';
    return 0;
}

Compilation message (stderr)

xanadu.cpp: In function 'long long int cnt(long long int, long long int, std::vector<long long int>, long long int)':
xanadu.cpp:9:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
    9 |   for(int p : c) sum+=p; if(sum==0) return 0;
      |   ^~~
xanadu.cpp:9:26: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
    9 |   for(int p : c) sum+=p; if(sum==0) return 0;
      |                          ^~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 10
• Subtask 4: 0 / 40
• Subtask 5: 0 / 30