Submission #1024946

#	Time	Username	Problem	Language	Result	Execution time	Memory
1024946		ach00	Graph (BOI20_graph)	C++14	0 / 100	1 ms	2652 KiB

Graph

#include <bits/stdc++.h>
using namespace std;
typedef long double ld;
#define A first
#define X second
#define EPS 0.00001
int n,m;
vector<ld> ans(100005, numeric_limits<ld>::max());
vector<vector<pair<int,int>>> adj; 
vector<pair<int,int>> prelim(100005, {0, 0});
vector<int> arrthing;
ld start_value = numeric_limits<ld>::max();
void explore(int v, int p) {
    if(prelim[v].X == 0) {
        prelim[v].X = 1;
    }
    int x = prelim[v].X;
    int a = prelim[v].A;
    if((a < 0 && x < 0) || (a > 0 && x > 0)) arrthing.push_back(-abs(a));
    else arrthing.push_back(abs(a));
    for(auto &e : adj[v]) {
        if(start_value != numeric_limits<ld>::max()) return;
        int u = e.first;
        int c = e.second;
        if(u == p) continue;
        if(prelim[u].X == 0) {
            prelim[u].X = -1*x;
            prelim[u].A = c - a;
            explore(u, v);
        } else {
            if(prelim[u].X + x == 0) {
                if(prelim[u].A + a != c) {
                    cout << "NO";
                    exit(0);
                }
            }
            start_value = ((ld)x)*((ld)(c-a-prelim[u].A))/(2.0);
            return;
        }
    }
}
void assign(int v) {
    for(auto &e : adj[v]) {
        int u = e.first;
        ld c = (ld)e.second;
        ld nans = c - ans[v];
        if(ans[u] != numeric_limits<ld>::max()) {
            if(abs(ans[u] - nans) < EPS) continue;
            cout << "NO";
            exit(0);
        } else {
            ans[u] = nans;
            assign(u);
        }
    }
}

int main() {
    cin >> n >> m;
    ans.resize(n);
    adj.resize(n);
    for(int i = 0; i < m; i++) {
        int a,b,c; cin >> a >> b >> c; a--; b--;
        adj[a].push_back({b,c});
        adj[b].push_back({a,c});
    }
    for(int i = 0; i < n; i++) {
        if(ans[i] != numeric_limits<ld>::max()) continue;
        start_value = numeric_limits<ld>::max();
        arrthing = {};
        explore(i, -1);
        if(start_value != numeric_limits<ld>::max()) {
            ans[i] = start_value;
            assign(i);
        } else {
            sort(arrthing.begin(), arrthing.end());
            ans[i] = (arrthing.size() != 0) ? ((ld)(arrthing[(arrthing.size())/2] + arrthing[(arrthing.size()-1)/2]))/2.0 : 0;
            assign(i);
        }
    }
    cout << "YES\n";
    for(int i = 0; i < n; i++) {
        cout << ans[i] << ' ';
    }
}

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