Submission #120955

#	Time	Username	Problem	Language	Result	Execution time	Memory
120955		thiago4532	Pipes (BOI13_pipes)	C++17	65 / 100	379 ms	29880 KiB

pipes

#include <bits/stdc++.h>
#define int int64_t

using namespace std;
typedef pair<int, int> pii;
const int maxn = 1e5 + 10;
const int maxm = 5e5 + 10;
vector<int> grafo[maxn];
int n;
int s[maxn];
map<pair<int, int>, int> mapa;
int val[maxn], ans[maxn];
int grau[maxn];

namespace tree{

int nivel[maxn], pai[maxn], soma[maxn];
void dfs(int u, int p = 0) {
	pai[u] = p;

	for(auto v : grafo[u]) {
		if(v == p) continue;
		nivel[v] = nivel[u] + 1;
		dfs(v, u);
	}
}

};

namespace cycle {
vector<int> grafo[maxn];
int st;

bool mark[maxn];
vector<int> ordem;

void dfs(int u) {
	mark[u] = true;
	ordem.push_back(u);

	for(auto v : grafo[u]) {
		if(!mark[v]) dfs(v);
	}
}

void solve() {
	dfs(st);
	if(ordem.size() % 2 == 0){
		cout << "0\n";
		return;
	}

	int x = 0;
	int sig = 1;
	for(auto& u : ordem){
		x += s[u]*sig;
		sig *= -1;
	}
	x/=2;

	ans[mapa[{ordem[0], ordem.back()}]] = x;
	// cout << ordem[0] << " " << ordem.back() << ": " << ans[mapa[{ordem[0], ordem.back()}]] << "\n";
	for(int i = 0; i < (int)ordem.size() - 1; i++) {
		ans[mapa[{ordem[i], ordem[i+1]}]] = s[ordem[i]] - x;
		// cout << ordem[i] << " " << ordem[i+1] << ": " << s[ordem[i]] - x << "\n";
		x = s[ordem[i]] - x;
	}

	for(int i=1;i<=n;i++){
		cout << ans[i] << "\n";
	}
}

};

int32_t main() {
	int m;

	cin >> n >> m;
	if(m > n) {
		cout << "0\n";
		return 0;
	}
	int total = 0;
	for(int i=1;i<=n;i++)
		cin >> s[i], s[i] *= 2, total += s[i];

	for(int i=1;i<=m;i++) {
		int a, b;
		cin >> a >> b;
		grafo[a].push_back(b);
		grafo[b].push_back(a);
		mapa[{a, b}] = i;
		mapa[{b, a}] = i;

		grau[a]++;
		grau[b]++;
	}
	if(n - 1 == m) {
		tree::dfs(1);
		vector<pii> arr;
		for(int i=1;i<=n;i++)
			arr.push_back({tree::nivel[i], i});
		sort(arr.begin(), arr.end(), greater<pii>());

		for(auto e : arr) {
			int v = e.second;
			int u = tree::pai[v];

			tree::soma[u] += (s[v] - tree::soma[v]);
			ans[mapa[{u, v}]] = (s[v] - tree::soma[v]);
		}

		if(tree::soma[1] != s[1]){
			cout << "0\n";
			return 0;
		}

		for(int i=1;i<=m;i++)
			cout << ans[i] << "\n";

	}else { // n == m
		bool only_cycle = true; // only cycle
		for(int i=1;i<=n;i++)
			if(grau[i] == 1) only_cycle = false;

		if(only_cycle) {
			for(int i=1;i<=n;i++)
				cycle::grafo[i] = grafo[i];
			cycle::st = 1;

			cycle::solve();
		}else {

		}
	}
	return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 35 / 70