Submission #672790

#	Time	Username	Problem	Language	Result	Execution time	Memory
672790		vjudge1	The Xana coup (BOI21_xanadu)	C++11	100 / 100	118 ms	32212 KiB

xanadu

/*#pragma GCC optimize ("O3")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")*/
#include <bits/stdc++.h>
#include <set>
#include <map>
using namespace std;
#define ll long long
#define N (ll)((ll)1e5+5)
#define M ((ll)998244353)
#define fi first
#define se second
ll n, dp[N][2][2], k;
bool on[N];
vector<ll> v[N];
vector<ll> p[N][2];
void dfs(ll s, ll par) {
	dp[s][0][0] = dp[s][0][1] = dp[s][1][0] = dp[s][1][1] = N;
	ll a, b; a = b = 0; for (auto x : v[s]) if (x != par) {
		dfs(x, s);
		p[s][0].push_back(dp[x][0][1] - dp[x][0][0]); a += dp[x][0][0];
		p[s][1].push_back(dp[x][1][1] - dp[x][1][0]); b += dp[x][1][0];
	}
	sort(p[s][0].begin(), p[s][0].end()), sort(p[s][1].begin(), p[s][1].end());
	dp[s][on[s]][0] = a; dp[s][on[s] ^ 1][1] = b + 1;
	for (int i = 0; i < p[s][0].size(); i++) {
		a += p[s][0][i]; b += p[s][1][i];
		dp[s][on[s] ^ (i & 1) ^ 1][0] = min(dp[s][on[s] ^ (i & 1) ^ 1][0], a);
		dp[s][on[s] ^ (i & 1)][1] = min(dp[s][on[s] ^ (i & 1)][1], b + 1);
	}
}
int32_t main() {
#define int ll
	ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	ll a, b; cin >> n; for (int i = 1; i < n; i++) cin >> a >> b, v[a].push_back(b), v[b].push_back(a); for (int i = 1; i <= n; i++) cin >> on[i];
	dfs(1, 0); if (min(dp[1][0][0], dp[1][0][1]) >= n) cout << "impossible";
	else cout << min(dp[1][0][0], dp[1][0][1]);
}

Compilation message (stderr)

xanadu.cpp: In function 'void dfs(long long int, long long int)':
xanadu.cpp:26:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   26 |  for (int i = 0; i < p[s][0].size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~~

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