Submission #315761

#	Time	Username	Problem	Language	Result	Execution time	Memory
315761		KWang31	Graph (BOI20_graph)	Java	34 / 100	815 ms	57920 KiB

Graph

import java.io.*; import java.util.*;
public class Graph {
    
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(br.readLine());
        int N=Integer.parseInt(st.nextToken());
        int M=Integer.parseInt(st.nextToken());
        ArrayList<Integer> arl[]=new ArrayList[N];
        for (int i = 0; i < N; i++) {
            arl[i]=new ArrayList<>();
        }
        int a,b,vv;
        for (int i = 0; i < M; i++) {
            st=new StringTokenizer(br.readLine());
            a=Integer.parseInt(st.nextToken())-1;
            b=Integer.parseInt(st.nextToken())-1;
            vv=Integer.parseInt(st.nextToken());
            arl[a].add(4*b+2*vv); arl[b].add(4*a+2*vv);
        }
        
        boolean[] vis=new boolean[N];
        
        int[] m=new int[N];
        int[] c=new int[N];
        int done=0; int pt=0;
        while(done<N){
            while(pt<N && vis[pt]){
                pt++;
            }
            
            //Start DFS at pt, finish the component
            m[pt]=1; //b[pt]=0
            Queue<Integer> qu=new LinkedList<>();
            qu.add(pt); vis[pt]=true; done++;
            ArrayList<Integer> qu2=new ArrayList<>();//Tracks all vertices in the queue
            qu2.add(pt); boolean fix=false;
            int x,y;
            while(!qu.isEmpty()){
                int v=qu.poll(); 
                for (int p : arl[v]) {
                    x=4-p%4; y=(p-x)/4;
                    if(!vis[y]){
                        vis[y]=true; qu.add(y); 
                        if(!fix){
                            qu2.add(y);
                        }
                        m[y]=-m[v]; c[y]=x-c[v]; done++;
                    }else{
                        //System.out.println(x+" "+y+" "+v);
                        if(m[y]==m[v] && m[v]!=0){
                            //m[p.vtx]x+c[p.vtx]+m[v]x+c[v] is known
                            int xx=(x-c[y]-c[v])/(2*m[y]); fix=true;
                            
                            for(int vtx: qu2){
                                
                                c[vtx]+=m[vtx]*xx; m[vtx]=0;
                            }
                        }else if(m[y]+m[v]==0){//m[v]=0
                            if(c[y]+c[v]!=x){
                                System.out.println("NO"); return;
                            }
                        }
                    }
                }
                //System.out.println(Arrays.toString(m));
                //System.out.println(Arrays.toString(c));
            }
            
            if(m[pt]!=0){//This component is not fixed
                ArrayList<Integer> arl2=new ArrayList<>();
                
                for (int i : qu2) {
                    if(m[i]<0){
                        m[i]=-m[i]; c[i]=-c[i]; qu.add(i);
                    }
                    arl2.add(c[i]);
                }
                
                Collections.sort(arl2);
                int med=arl2.get(arl2.size()/2);
                for (int i : qu2) {
                    c[i]-=med;
                    
                }
                while(!qu.isEmpty()){
                    int i=qu.poll();
                    c[i]=-c[i];
                }
            }
            
        }
        System.out.println("YES");
        StringBuilder sb=new StringBuilder();
        for (int i = 0; i < N; i++) {
             sb.append((double)c[i]/2).append(" ");
        }
        System.out.println(sb.toString());
    }
    
}

Compilation message (stderr)

Note: Graph.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

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