Submission #315737

#	Time	Username	Problem	Language	Result	Execution time	Memory
315737		KWang31	Graph (BOI20_graph)	Java	0 / 100	82 ms	10596 KiB

Graph

import java.io.*; import java.util.*;
public class Graph {
    public static class Pair{
        int vtx; int val;
        public Pair(int a, int b){
            this.vtx=a; this.val=b;
        }
    }
    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<Pair> 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(new Pair(b,2*vv)); arl[b].add(new Pair(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++;
            Queue<Integer> qu2=new LinkedList<>();//Tracks all vertices in the queue
            qu2.add(pt); boolean fix=false;
            while(!qu.isEmpty()){
                int v=qu.poll(); 
                for (Pair p : arl[v]) {
                    if(!vis[p.vtx]){
                        vis[p.vtx]=true; qu.add(p.vtx); 
                        if(!fix){
                            qu2.add(p.vtx);
                        }
                        m[p.vtx]=-m[v]; c[p.vtx]=p.val-c[v]; done++;
                    }else{
                        if(m[p.vtx]==m[v] && m[v]!=0){
                            //m[p.vtx]x+c[p.vtx]+m[v]x+c[v] is known
                            int x=(p.val-c[p.vtx]-c[v])/(2*m[p.vtx]); fix=true;
                            
                            for(int vtx: qu2){
                                
                                c[vtx]+=m[vtx]*x; m[vtx]=0;
                            }
                        }else if(m[p.vtx]+m[v]==0){//m[v]=0
                            if(c[p.vtx]+c[v]!=p.val){
                                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<>();
                //Queue<Integer> qu3=new LinkedList<>();
                while (!qu2.isEmpty()) {
                    int i=qu2.poll();
                    if(m[i]<0){
                        m[i]=-m[i]; c[i]=-c[i]; qu2.add(i);
                    }
                    arl2.add(c[i]);
                }
                Collections.sort(arl2);
                int med=arl2.get(arl2.size()/2);
                for (int i : qu2) {
                    c[i]-=med;
                    
                }
                while(!qu2.isEmpty()){
                    int i=qu2.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: 0 / 5
• Subtask 2: 0 / 12
• Subtask 3: 0 / 17
• Subtask 4: 0 / 24
• Subtask 5: 0 / 42