Submission #802661

#	Time	Username	Problem	Language	Result	Execution time	Memory
802661		amirhoseinfar1385	Graph (BOI20_graph)	C++17	100 / 100	111 ms	28920 KiB

Graph

#include<bits/stdc++.h>
using namespace std;
const int maxn=100000+10;
vector<pair<int,int>>adj[maxn],adjt[maxn];
int isr[maxn],vis[maxn],n,m,high[maxn],resf[maxn],resz[maxn],val[maxn];
int res=1,timea=0;
vector<int>now;

void dfs(int u){
	if(vis[u]==1){
		return ;
	}
	now.push_back(u);
	isr[u]=1;
	vis[u]=1;
	for(auto xx:adj[u]){
		int x=xx.first;
		int y=xx.second;
		if(vis[x]==0){
			adjt[u].push_back(xx);
			adjt[x].push_back(make_pair(u,xx.second));
			high[x]=high[u]+1;
			if(high[u]&1){
				resf[x]=resf[u];
				resz[x]=resz[u]+y;
			}
			else{
				resf[x]=resf[u]+y;
				resz[x]=resz[u];
			}
			dfs(x);
		}
	}
}

pair<int,int> checkalle(){
	for(auto x:now){
		for(auto xx:adj[x]){
			int y=xx.first;
			if(high[x]<high[y]){
				continue;
			}
			if(high[x]==high[y]+1){
				continue;
			}
			int sf=resf[x]-resf[y],sz=resz[x]-resz[y];
			if((high[x]&1)!=(high[y]&1)){
				if(high[x]&1){
					sz+=xx.second;
				}
				else{
					sf+=xx.second;
				}
				if(sz==sf){
					continue;
				}
				return make_pair(-2,-2);
			}
			if(high[x]&1){
				sf+=xx.second;
			}
			else{
				sz+=xx.second;
			}
			if(sz==sf){
				return make_pair(x,0);
				continue;
			}
			int ss;
			if(high[x]&1){
				ss=sf-sz;
			}	
			else{
				ss=sz-sf;
			}
			ss/=2;
			//ss=-ss;
			//cout<<x<<" "<<ss<<" "<<sz<<" "<<sf<<"wtf\n";
			return make_pair(x,ss);
		}
	}
	return make_pair(-1,-1);
}

int por(int u,int w,int par=0){
	//cout<<u<<" "<<w<<" "<<par<<" asd\n";
	val[u]=w;
	int ret=abs(w);
	for(auto x:adjt[u]){
		if(x.first!=par){
			ret+=por(x.first,x.second-w,u);
		}
	}
	return ret;
}

void solve(int u){
	now.clear();
	dfs(u);
	pair<int,int>fixy=checkalle();
	if(fixy.first==-2){
		res=0;
		return ;
	}
	//cout<<u<<" "<<endl;
	if(fixy.first!=-1){
		por(fixy.first,fixy.second);
		return ;
	}
	int low=-1000,high=1000,w,mid;
	while(high-low>1){
		mid=(high+low)>>1;
		long long av=por(u,mid),dov=por(u,mid+1);
		//cout<<high<<" "<<low<<" "<<mid<<" "<<av<<" "<<dov<<"\n";
		if(av>=dov){
			low=mid;
		}
		else{
			high=mid;
		}
	}
	if(por(u,low)<por(u,high)){
		w=low;		
	}
	else{
		w=high;
	}
	//cout<<por(u,0)<<" "<<por(u,2)<<" "<<mina<<" "<<w<<"\n";
	por(u,w);
}

void checkakh(){
	for(int i=1;i<=n;i++){
		for(auto x:adj[i]){
			int y=x.first;
			//cout<<val[i]<<" "<<val[y]<<" "<<x.second<<"\n";
			if(val[i]+val[y]!=x.second){
				res=0;
				return ;
			}
		}
	}
}

int main(){
	ios::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;
		w*=2;
		adj[u].push_back(make_pair(v,w));
		adj[v].push_back(make_pair(u,w));
	}
	for(int i=1;i<=n;i++){
		if(isr[i]==0){
			//cout<<"ha: "<<i<<"\n";
			solve(i);
		}
	}
	////cout<<res<<"\n";
	checkakh();
	if(res==0){
		cout<<"NO\n";
		return 0;
	}
	cout<<"YES\n";
	cout<<setprecision(2);
	for(int i=1;i<=n;i++){
		if(val[i]<0){
			cout<<"-";
		}
		val[i]=abs(val[i]);
		if((val[i]&1)==1){
			val[i]/=2;
			cout<<val[i];
			cout<<".5";
		}
		else{
			val[i]/=2;
			cout<<val[i];
		}
		cout<<" ";
	}
	cout<<"\n";
}

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