Submission #932281

#	Time	Username	Problem	Language	Result	Execution time	Memory
932281		Ghulam_Junaid	Graph (BOI20_graph)	C++17	58 / 100	187 ms	16072 KiB

Graph

#include <bits/stdc++.h>
using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e5 + 10;
int n, m;
bool vis[N];

vector<double> poss;
vector<int> path;
vector<pair<int, double>> g[N], loops;

double val[N], ans[N];
long double sm;

void getpath(int v){
    vis[v] = 1;
    path.push_back(v);
    for (auto [u, w] : g[v])
        if (!vis[u]) getpath(u);
}

void dfs(int v){
    vis[v] = 1;
    sm += abs(val[v]);
    for (auto [u, w] : g[v]){
        if (vis[u]){
            if (val[u] == w - val[v])
                continue;
            val[u] = 1e9;
            sm += 1e9;
            return;
        }
        
        val[u] = w - val[v];
        dfs(u);
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

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

        if (u == v)
            loops.push_back({v, w});
    }

    for (auto [v, w] : loops){
        if (vis[v]) continue;
        
        path.clear();
        getpath(v);
        for (int u : path)
            vis[u] = 0;

        val[v] = w / 2;
        dfs(v);

        for (int u : path){
            ans[u] = val[u];
            if (ans[u] >= 1e9){
                cout << "NO" << endl;
                return 0;
            }
        }
    }

    poss.push_back(0);
    for (double i = 0; i < 10; i ++){
        poss.push_back(i + 0.5);
        if (i < 4)
            poss.push_back(i + 1);
    }

    for (int i = 1; i <= n; i ++){
        if (vis[i]) continue;

        path.clear();
        getpath(i);
        for (int v : path)
            vis[v] = 0;

        double mn = 1e9;
        int sz = path.size();
        for (int r = 0; r < 7; r ++){
            for (double x : poss){

                int ind = rng() % sz;
                int node = path[ind];

                if (!r) node = i;

                sm = 0;
                val[node] = x;
                dfs(node);

                if (mn > sm){
                    mn = sm;
                    for (int v : path){
                        vis[v] = 0;
                        ans[v] = val[v];
                    }
                }
                else{
                    for (int v : path)
                        vis[v] = 0;
                }
            }
        }

        for (int v : path) vis[v] = 1;

        if (mn == 1e9){
            cout << "NO" << endl;
            return 0;
        }
    }

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

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 17 / 17
• Subtask 4: 24 / 24
• Subtask 5: 0 / 42