Submission #486034

#	Time	Username	Problem	Language	Result	Execution time	Memory
486034		chungdinh	Graph (BOI20_graph)	C++17	100 / 100	242 ms	23480 KiB

Graph

#include <iostream>
#include <vector>
#include <cstring>
#include <queue>
#include <algorithm>

using namespace std;

#define ii pair<int, int>
#define MP make_pair

const int N = 5e5 + 5;
const int iINF = 1e9;
const double dINF = 10000;

int n, m;
vector<ii> g[N];

int vsd[N];

ii z[N];
double res[N];

double subsub(const ii& a, const ii& b) {
    if (a.first == b.first) {
        if (a.second == b.second) return dINF;
        else return -dINF;
    }
    return (double)(b.second - a.second) / (a.first - b.first);
}
ii transfer(ii a, int c) {return {-a.first, c - a.second};}

bool sub(int ux) {
    queue<int> q; q.push(ux);
    z[ux] = {1, 0};
    vsd[ux] = 0;
    res[ux] = -dINF;

    vector<int> lst;

    while (q.size()) {
        int u = q.front(); q.pop();

        {
            ii tmp = z[u];
            if (tmp.first < 0) tmp = {-tmp.first, -tmp.second};
            lst.push_back(-tmp.second);
        }

        for (ii a : g[u]) {
            int v = a.first, c = a.second;

            if (vsd[v] < 0) {
                z[v] = transfer(z[u], c);
                vsd[v] = ux;
                q.push(v);
            } else {
                double tmp = subsub(transfer(z[u], c), z[v]);
                //cout << u << " " << v << " " << tmp << endl;

                if (tmp == dINF) continue;
                else if (tmp == -dINF) return false;
                else {
                    if (res[ux] == -dINF || res[ux] == tmp) res[ux] = tmp;
                    else return false;
                }
            }
        }
    }
    if (res[ux] == -dINF) {
        sort(lst.begin(), lst.end());
        res[ux] = lst[lst.size() / 2];
    }

    //cout << ux << " " << res[ux] << endl;

    return true;
}

int main() {
    #ifdef CHUNGDINH
    freopen("main.inp", "r", stdin);
    #endif // CHUNGDINH

    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int u, v, c; cin >> u >> v >> c;
        g[u].push_back(MP(v, c));
        g[v].push_back(MP(u, c));
    }

    for (int i = 1; i <= n; i++) vsd[i] = -1;
    for (int i = 1; i <= n; i++) if (vsd[i] < 0) {
        if (!sub(i)) {
            cout << "NO";
            return 0;
        }
    }

    //for (int i = 1; i <= n; i++) cout << z[i].first << " " << z[i].second << endl;

    cout << "YES\n";
    for (int i = 1; i <= n; i++) {
        if (!vsd[i]) {}
        else res[i] = res[vsd[i]] * z[i].first + z[i].second;

        cout << res[i] << " ";
    }
}

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