No DFS is needed for the problem you pose here. It can be solved in a
single pass through the input.
On Mar 27, 2013 5:16 PM, "mandeep khatkar" <mandeep...@gmail.com> wrote:
> Problem:-
> Suppose that you are given no. 1 2,2 3,4 5 so here 1,2,3 will share same
> path because of transitive relation between them and 4,5 will share other
> route....and even if u are given no. like 1 2,3 4,1 4 then in this case
> 1,2,3,4 will share same path...so you will have to output total no of
> path....i know it includes DFS.but still i am getting some error in
> output...here is my code...
> Input:-
> 1 2
> 3 4
> 1 4
> 6 7
> Ouput:-2 ({1,2,3,4},{6,7})
>
> /*
> * To change this template, choose Tools | Templates
> * and open the template in the editor.
> */
> package chef;
> import java.io.BufferedReader;
> import java.io.IOException;
> import java.io.InputStreamReader;
> import java.math.BigInteger;
> import java.util.StringTokenizer;
> /**
> *
> * @author Pardeep
> */
> public class pathshare {
>
> public static void main(String a[]) throws IOException
> {
> BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
> int t=Integer.parseInt(br.readLine());
> for(int tes=0;tes<t;tes++){
> StringTokenizer st=new StringTokenizer(br.readLine());
> int n=Integer.parseInt(st.nextToken());
> //String ar[]=new String[n+1];
> int pre[]=new int[n+1];
> long val[]=new long[n+1];
> int sto[]=new int[n+1];
> //int relst[]=new int[n+1];
> boolean setflag=false;
> boolean visit[]=new boolean[n+1];
> for(int i=1;i<=n;i++)
> {
> //ar[i]=String.valueOf(i);
> pre[i]=i;
> visit[i]=false;
> val[i]=1;
> }
> int rel=Integer.parseInt(st.nextToken());
> // int stack[]=new
> int[1000000];
> int len=0;
>
> while(rel>=1){
> setflag=true;
> st=new StringTokenizer(br.readLine());
> int e1=Integer.parseInt(st.nextToken());
> //stack[len++]=e1;
> int e2=Integer.parseInt(st.nextToken());
> if(!visit[e2]||!visit[e1])
> {
> int ch=pre[e2];int ch1=pre[e1];
> if(pre[ch]!=pre[e2]&&visit[e2]){
> pre[e2]=pre[ch];
> ch=pre[e2];
> }
> if(pre[ch1]!=pre[e1]&&visit[e1]){
> // System.out.println("upr");
> pre[e1]=pre[ch1];
> ch1=pre[e1];
> }
> //System.out.println("pr.."+pre[e1]+" "+pre[ch1]);
> if(!visit[e1]&&visit[e2]){
> pre[e1]=pre[e2];
> val[pre[e1]]+=1;
> visit[e1]=true;
> }
> else if(visit[e1]&&!visit[e2]){
>
> pre[e2]=pre[e1];//System.out.println("checking...."); //1
> 2,3 4,1 4
> val[pre[e2]]+=1;visit[e2]=true;
> }
> else if(!visit[e1]&&!visit[e2]){
> pre[e2]=pre[e1];
> val[pre[e2]]+=1;
> visit[e2]=visit[e1]=true;
> }
> //visit[e2]=visit[e1]=true;
> //System.out.println("ar: "+val[pre[e1]]+" "+pre[e1]);
> //}
> }
> else if((visit[e2]&&visit[e1])&&pre[e2]!=pre[e1]){
> val[pre[e1]]+=val[pre[e2]];
> int ch=pre[e2];val[pre[e2]]=1;
> while(ch!=pre[e1]){
> pre[ch]=pre[e1];
> ch=pre[ch];//System.out.println("lwr");
> }
> pre[e2]=pre[e1];
> // System.out.println("visited.. "+val[pre[e1]]+" "+pre[e2]);
> }
> rel--;
> }
> BigInteger vallen= BigInteger.valueOf(1);
> len=0;long mod=1000000007;
> long valrel=0;boolean flag=false;long vf=0;boolean zero=false;
> //for(int i=1;i<=n;i++) System.out.println(val[i]+" "+visit[i]);
> for(int i=1;i<=n;i++){
>
> if(val[i]==1&&!visit[i]){
>
> //System.out.println("computing.... 1");
> valrel++;zero=true;
> }
> else if(val[i]>1&&visit[i]&&vf!=0){
> //System.out.println("computing..O");
>
> vallen=vallen.multiply(BigInteger.valueOf(val[i])).mod(BigInteger.valueOf(mod));//System.out.println("m"+vallen);
> //System.out.println("l.."+vallen);
> valrel++;//len++;
> flag=true;zero=true;
> }
> else if(val[i]>1&&visit[i]&&vf==0){
> vf=val[i];valrel++;flag=true;
> }
>
> }
> //if(!flag){ vallen=BigInteger.valueOf(1);vf=1;}
> //if(!zero){vallen=BigInteger.valueOf(vf);}
> // else
> {vallen=vallen.multiply(BigInteger.valueOf(vf)).mod(BigInteger.valueOf(mod));}
>
> //if(rel==0&&setflag==false){vf=0;vallen=vallen.multiply(BigInteger.ZERO);}
> //System.out.println(bg);
> System.out.println(valrel);
> //System.out.println((valrel%mod)+" "+(vallen%mod));
> }}
> }
>
>
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