Submission #536336

#	Time	Username	Problem	Language	Result	Execution time	Memory
536336		skittles1412	Graph (BOI20_graph)	C++17	100 / 100	190 ms	30612 KiB

Graph

#include "bits/extc++.h"

using namespace std;

template <typename T>
void dbgh(const T& t) {
	cerr << t << endl;
}

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
	cerr << t << " | ";
	dbgh(u...);
}

#ifdef DEBUG
#define dbg(...)                                           \
	cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]" \
		 << ": ";                                          \
	dbgh(__VA_ARGS__)
#else
#define cerr   \
	if (false) \
	cerr
#define dbg(...)
#endif

using ld = long double;

#define endl "\n"
#define long int64_t
#define sz(x) int((x).size())

const int maxn = 1e5;
const ld UNKNOWN = 1e9, EPS = 1e-6;

vector<int> vals;
vector<pair<int, int>> graph[maxn];
bool found, vis[maxn];
int depth[maxn];
ld ans[maxn];

void dfs2(int u) {
	for (auto& [v, e] : graph[u]) {
		if (ans[v] == UNKNOWN) {
			ans[v] = e - ans[u];
			dfs2(v);
		} else if (abs(e - ans[u] - ans[v]) > EPS) {
			dbg(u, v, ans[u], ans[v]);
			cout << "NO" << endl;
			exit(0);
		}
	}
}

void dfs1(int u, int d) {
	static vector<pair<int, int>> st;
	if (found) {
		return;
	}
	if (vis[u]) {
		if ((d - depth[u]) % 2 == 0) {
			return;
		}
		found = true;
		ld sum = 0;
		vector<pair<int, int>> cur;
		for (int i = sz(st) - 1; i >= 0; i--) {
			if (i < sz(st) - 1 && st[i].first == u) {
				break;
			}
			cur.push_back(st[i]);
		}
		for (auto& [_, x] : cur) {
			sum += x;
		}
		sum /= 2;
		for (int i = 1; i < sz(cur); i += 2) {
			sum -= cur[i].second;
		}
		dbg(cur[0].first, sum);
		ans[cur[0].first] = sum;
		dfs2(cur[0].first);
		return;
	}
	vis[u] = true;
	depth[u] = d;
	for (auto& [v, e] : graph[u]) {
		st.emplace_back(v, e);
		dfs1(v, d + 1);
		st.pop_back();
	}
}

void dfs3(int u, int s, bool neg) {
	if (vis[u]) {
		return;
	}
	dbg(s);
	if (neg) {
		vals.push_back(-s);
	} else {
		vals.push_back(s);
	}
	vis[u] = true;
	for (auto& [v, e] : graph[u]) {
		dfs3(v, e - s, !neg);
	}
}

void solve() {
	int n, m;
	cin >> n >> m;
	int edges[m][3];
	for (auto& [u, v, w] : edges) {
		cin >> u >> v >> w;
		u--;
		v--;
		graph[u].emplace_back(v, w);
		graph[v].emplace_back(u, w);
	}
	fill(begin(ans), end(ans), UNKNOWN);
	for (int i = 0; i < n; i++) {
		if (!vis[i] && ans[i] == UNKNOWN) {
			found = false;
			dbg(i);
			dfs1(i, 0);
		}
	}
	memset(vis, 0, sizeof(vis));
	dbg("A");
	for (int i = 0; i < n; i++) {
		if (ans[i] == UNKNOWN) {
			vals.clear();
			dfs3(i, 0, true);
			sort(begin(vals), end(vals));
			ans[i] = vals[sz(vals) / 2];
			dfs2(i);
		}
	}
	for (auto& [u, v, w] : edges) {
		assert(abs(w - ans[u] - ans[v]) <= EPS);
	}
	cout << "YES" << endl;
	for (int i = 0; i < n; i++) {
		cout << ans[i] << " \n"[i == n - 1];
	}
}

int main() {
	cout << fixed << setprecision(9);
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	cin.exceptions(ios::failbit);
	solve();
}

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 17 / 17
• Subtask 4: 24 / 24
• Subtask 5: 42 / 42