Submission #205064

#	Time	Username	Problem	Language	Result	Execution time	Memory
205064		mode149256	Pipes (BOI13_pipes)	C++14	100 / 100	316 ms	42232 KiB

pipes

/*input
3 3
9
4
6
1 2
2 3
3 1

7 7
2
2
2
2
2
2
2
1 2
2 3
3 4
4 5
5 6
6 7
7 1
*/
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;

typedef vector<int> vi;
typedef vector<vi> vii;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<vl> vll;
typedef vector<pi> vpi;
typedef vector<vpi> vpii;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
typedef vector<pd> vpd;
typedef vector<bool> vb;
typedef vector<vb> vbb;
typedef std::string str;
typedef std::vector<str> vs;

#define x first
#define y second
#define debug(...) cout<<"["<<#__VA_ARGS__<<": "<<__VA_ARGS__<<"]\n"

const int MOD = 1000000007;
const ll INF = std::numeric_limits<ll>::max();
const int MX = 500101;
const ld PI = 3.14159265358979323846264338327950288419716939937510582097494L;

template<typename T>
pair<T, T> operator+(const pair<T, T> &a, const pair<T, T> &b) { return pair<T, T>(a.x + b.x, a.y + b.y); }
template<typename T>
pair<T, T> operator-(const pair<T, T> &a, const pair<T, T> &b) { return pair<T, T>(a.x - b.x, a.y - b.y); }
template<typename T>
T operator*(const pair<T, T> &a, const pair<T, T> &b) { return (a.x * b.x + a.y * b.y); }
template<typename T>
T operator^(const pair<T, T> &a, const pair<T, T> &b) { return (a.x * b.y - a.y * b.x); }

template<typename T>
void print(vector<T> vec, string name = "") {
	cout << name;
	for (auto u : vec)
		cout << u << ' ';
	cout << '\n';
}

vl W(MX);
int N, M;
vector<vpi> edges(MX);
vi sz(MX, 0);
vb done(MX, false);
vl ats(MX, -1);

void bad() {
	printf("0\n");
	exit(0);
}

vb visited(MX, false);
int cnt = 0;
void dfs(int v) {
	cnt++;
	visited[v] = true;
	for (auto u : edges[v])
		if (!visited[u.x] and !done[u.y])
			dfs(u.x);
}

vi nodes;
vi edg;
int prad;

void dfs2(int v, int p) {
	if (visited[v]) return;
	nodes.push_back(v);
	visited[v] = true;

	for (auto u : edges[v]) {
		if (!done[u.y] and u.x != p) {
			edg.push_back(u.y);
			dfs2(u.x, v);
			break;
		}
	}
}

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	cin >> N >> M;
	for (int i = 0; i < N; ++i)
		cin >> W[i];

	for (int i = 0; i < M; ++i)
	{
		int a, b;
		cin >> a >> b; a--; b--;
		sz[a]++;
		sz[b]++;
		edges[a].push_back({b, i});
		edges[b].push_back({a, i});
	}

	queue<int> vienas;
	for (int i = 0; i < N; ++i)
	{
		if (sz[i] == 1)
			vienas.push(i);
	}

	while (vienas.size()) {
		int c = vienas.front(); vienas.pop();

		for (auto u : edges[c]) {
			if (done[u.y]) continue;

			sz[c]--;
			sz[u.x]--;
			done[u.y] = true;
			ats[u.y] = 2 * W[c];
			W[u.x] -= W[c];
			if (sz[u.x] == 1)
				vienas.push(u.x);
			break;
		}
	}

	bool visi2 = true;
	for (int i = 0; i < N; ++i)
	{
		if (sz[i] != 2 and sz[i] != 0) {
			visi2 = false;
			break;
		}
	}

	if (!visi2) bad();

	for (int i = 0; i < N; ++i)
	{
		if (visited[i]) continue;
		cnt = 0;
		dfs(i);
		if (cnt % 2 == 0) bad();
	}

	visited = vb(MX, false);

	auto daryk = [&]() {
		int K = (int)nodes.size();

		ll visux = 0;

		for (int i = 0; i < K; ++i)
			visux += W[nodes[i]];


		// printf("visux = %lld\n", visux);

		ll curr = 0;
		for (int i = 0; i < K; i += 2)
			curr += 2 * W[nodes[i]];

		for (int i = 0; i < K; i += 2)
		{
			curr -= 2 * W[nodes[i]];

			ats[edg[i]] = visux - curr;

			if (i + 1 < K)
				curr += 2 * W[nodes[i + 1]];
		}

		curr = 0;
		for (int i = 1; i < K; i += 2)
			curr += 2 * W[nodes[i]];

		for (int i = 1; i < K; i += 2)
		{
			curr += 2 * W[nodes[i - 1]];
			curr -= 2 * W[nodes[i]];

			ats[edg[i]] = visux - curr;
		}
	};

	for (int i = 0; i < N; ++i)
	{
		if (!visited[i]) {
			nodes.clear();
			edg.clear();
			dfs2(i, -1);
			if ((int)nodes.size() == 1) continue;
			// print(nodes);
			daryk();
		}
	}

	for (int i = 0; i < M; ++i)
		printf("%lld\n", ats[i]);
}

/* Look for:
* special cases (n=1?)
* overflow (ll vs int?)
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* array bounds
*/

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