Submission #1053811

#	Time	Username	Problem	Language	Result	Execution time	Memory
1053811		codexistent	Pipes (BOI13_pipes)	C++14	44.07 / 100	497 ms	100040 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MAXN 100005
#define MAXM 500005
#define FOR(i, a, b) for(ll i = a; i <= b; i++)
#define f first
#define s second

ll n, m, w[MAXN], d[MAXM];
set<ll> adj[MAXN];
pair<ll, pair<ll, ll>> e[MAXM];
bool v[MAXM];
map<pair<ll, ll>, ll> eid;

int main(){
    cin >> n >> m;
    FOR(i, 1, n) cin >> w[i];
    FOR(i, 1, m){
        e[i].f = 0;
        cin >> e[i].s.f >> e[i].s.s;
        adj[e[i].s.f].insert(e[i].s.s), adj[e[i].s.s].insert(e[i].s.f);

        eid.insert({{min(e[i].s.f, e[i].s.s), max(e[i].s.f, e[i].s.s)}, i});
    }

    priority_queue<pair<ll, ll>> pq;
    FOR(i, 1, m) {
        v[i] = false;
        e[i].f = adj[e[i].s.f].size() + adj[e[i].s.s].size() - 2;
        //cout << "FOR EDGE " << i << " WE HAVE " << e[i].f << " CT " << endl;
        for(auto j : adj[e[i].s.f]){
            if(j != e[i].s.s && adj[j].size() == 2 && adj[e[i].s.s].find(j) != adj[e[i].s.s].end()){
                e[i].f -= 2;
            }
        }

        if(e[i].f == 0){
            pq.push({0, i});
        } else if(adj[e[i].s.f].size() == 1 || adj[e[i].s.s].size() == 1){
            pq.push({1, i});
        }
    }
    while(pq.size()){
        //cout << pq.top().f << " ~ " << pq.top().s << " ==> " << e[pq.top().s].f << endl;
        auto pqi = pq.top(); pq.pop();
        if(v[pqi.s]) continue;
        v[pqi.s] = true;

        if(pqi.f == 0){
            ll s = 0;
            for(ll i2 : adj[e[pqi.s].s.f]) s += w[i2];
            for(ll i2 : adj[e[pqi.s].s.s]) s += w[i2];

            d[pqi.s] = w[e[pqi.s].s.f] + w[e[pqi.s].s.s] - s;
        }else if(adj[e[pqi.s].s.f].size() == 1){
            d[pqi.s] = w[e[pqi.s].s.f] * 2;
        }else{
            d[pqi.s] = w[e[pqi.s].s.s] * 2;
        }

        adj[e[pqi.s].s.f].erase(e[pqi.s].s.s);
        adj[e[pqi.s].s.s].erase(e[pqi.s].s.f);
        w[e[pqi.s].s.f] -= d[pqi.s] / 2;
        w[e[pqi.s].s.s] -= d[pqi.s] / 2;

        if(adj[e[pqi.s].s.f].size() == 2){
            ll a = *(adj[e[pqi.s].s.f].begin());
            ll b = *next(adj[e[pqi.s].s.f].begin(), 1);

            if(eid.find({min(a, b), max(a, b)}) != eid.end()){
                e[eid[{min(a, b), max(a, b)}]].f -= 2;

                if(!v[eid[{min(a, b), max(a, b)}]] && e[eid[{min(a, b), max(a, b)}]].f == 0){
                    pq.push({0, eid[{min(a, b), max(a, b)}]});
                }
            }
        }else if(adj[e[pqi.s].s.f].size() == 1){
            ll a = *(adj[e[pqi.s].s.f].begin());
            if(!v[eid[{min(a, e[pqi.s].s.f), max(a, e[pqi.s].s.f)}]]){
                pq.push({1, eid[{min(a, e[pqi.s].s.f), max(a, e[pqi.s].s.f)}]});
            }
        }

        if(adj[e[pqi.s].s.s].size() == 2){
            ll a = *(adj[e[pqi.s].s.s].begin());
            ll b = *next(adj[e[pqi.s].s.s].begin());

            if(eid.find({min(a, b), max(a, b)}) != eid.end()){
                e[eid[{min(a, b), max(a, b)}]].f -= 2;

                if(!v[eid[{min(a, b), max(a, b)}]] && e[eid[{min(a, b), max(a, b)}]].f == 0){
                    pq.push({0, eid[{min(a, b), max(a, b)}]});
                }
            }
        }else if(adj[e[pqi.s].s.s].size() == 1){
            ll a = *(adj[e[pqi.s].s.s].begin());
            if(!v[eid[{min(a, e[pqi.s].s.s), max(a, e[pqi.s].s.s)}]]){
                pq.push({1, eid[{min(a, e[pqi.s].s.s), max(a, e[pqi.s].s.s)}]});
            }
        }
    }

    FOR(i, 1, m) if(!v[i] || d[i] % 2 == 1){
        cout << 0 << endl;
        return 0;
    } 

    //FOR(i, 1, m) cout << d[i] << endl;
}

• Subtask 1: 0 / 30
• Subtask 2: 44.074074074074076 / 70