Submission #973805

#	Time	Username	Problem	Language	Result	Execution time	Memory
973805		NotLinux	Graph (BOI20_graph)	C++17	0 / 100	2 ms	3420 KiB

Graph

//author : FatihCihan
#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin() , v.end()
#define sz(a) (int)a.size()
const int N = 1e5 + 7;
const int inf = 1e9 + 7;
const double EPS = 0.000001;
const double INF = 1e9 + 7;
int n,m;
vector < pair < int , int > > graph[N];
pair < int , int > mem[N];//ax + b
void solve(){
	cin >> n >> m;
	for(int i = 0;i<=n;i++)mem[i] = {inf , inf};
	for(int i = 0;i<m;i++){
		int a,b,c;
		cin >> a >> b >> c;
		graph[a].push_back({b , c});
		graph[b].push_back({a , c});
	}
	queue < pair < int , pair < int , int > > > q;
	q.push({1 , {1 , 0}});
	set < double > possible;
	while(sz(q)){
		int node = q.front().first;
		pair < int , int > eq = q.front().second;
		q.pop();
		if(mem[node] != pair < int , int >{inf , inf}){// check whether it matches or not
			if(mem[node].first == eq.first and mem[node].second != eq.second){
				cout << "NO" << endl;
				return;
			}
			else if(mem[node].first == eq.first){
				37;
			}
			else{
				possible.insert((double)(mem[node].second - eq.second) / (double)(eq.first - mem[node].first));
			}
		}
		else{
			mem[node] = eq;
			// cout << node << " : " << eq.first << " , " << eq.second << endl;;
			for(auto itr : graph[node]){
				q.push({itr.first , {-eq.first , itr.second - eq.second}});
			}
		}
	}
	// cout << "possible : ";for(auto itr : possible)cout << itr << " ";cout << endl;
	auto answer = [&](double x){
		cout << "YES" << endl;
		for(int i = 1;i<=n;i++){
			cout << fixed << setprecision(6) << (double)mem[i].first * x + (double)mem[i].second << ' ';
		}
		cout << endl;
	};
	if(sz(possible) > 1){
		cout << "NO" << endl;
		return;
	}
	else if(sz(possible) == 1){
		// double ret = 0 , x = *possible.begin();
		// for(int i = 1;i<=n;i++){
		// 	ret += abs((double)mem[i].first * x + (double)mem[i].second);
		// }
		// cout << ret << endl;
		answer(*possible.begin());
	}
	else{
		// binary search ?
		auto check = [&](double x){
			double ret = 0;
			for(int i = 1;i<=n;i++){
				ret += abs((double)mem[i].first * x + (double)mem[i].second);
			}	
			return ret;
		};
		double l = 0 , r = INF;
		while(abs(l - r) > EPS){
			double mid = (l + r) / 2;
			if(check(mid) < check(mid + EPS)){
				r = mid;				
			}
			else{
				l = mid + EPS;
			}
		}
		// cout << check(l) << endl;
		answer(l);
	}
}
signed main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	int testcase = 1;//cin >> testcase;
	while(testcase--)solve();
	cerr << 1000.0 * clock() / CLOCKS_PER_SEC << " ms" << endl;
}

Compilation message (stderr)

Graph.cpp: In function 'void solve()':
Graph.cpp:35:5: warning: statement has no effect [-Wunused-value]
   35 |     37;
      |     ^~

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