Cojs 1001. [WZOI2011 S3] Message delivery

1001. [WZOI2011 S3] Message delivery

★ Import File: messagew.in output file: messagew.out Simple comparison
Time limit: 1 s memory limit: MB

Problem 2 Message delivery (MESSAGEW.PAS/C/CPP)

Problem Description

Wzland opened a club (which can do anything), which attracted a lot of people to join. The number of clubs is increasing and the relationship is becoming

more and more complex ...

The club's people came from all over the place, and in order to increase friendship, the club held a party. At the party, another word game, if a knows B, then a receives a message, it will pass the message to B, as well as all a know the person (if a knows b,b not necessarily know a), everyone from 1 to n number.

now given all the "know" relationships, the head of the club, Wzland's king, wants to know a very simple question: if a releases a new message, the message is passed back to A,1≤a≤n after several passes. But the king of Wzland is famous for his poor maths, but fortunately you are at his side, so he will give you this problem to solve.

Input Format

the first line in the input data is two numbers n and M, and there is a space between two numbers that represents the number of people and the number of cognitive relationships.

the next M-line, two numbers a and b for each line, indicates that a recognizes B (1 A, bn,ab).

output Format

a total of n rows in the output file, one character "T" or "F" per line. Line I if it is "T", means I send a new message will be passed back to I; if it is "F", means I send a new message will not be returned to I.

sample input and output

message.in

4 6

1 2

2 3

4 1

3 1

1 3

2 3

Message.out

T

T

T

F

Data Size

for 30% of data, n≤1000,m≤20000;

for 50% of data, n≤10000,m≤100000;

for 100% of data, n≤100000,m≤200000;

The cognitive relationship may be repeated.

time limit

1s

Exercises

Tarjan

AC Code:

#include <cstdio>#include<vector>#include<stack>using namespacestd;#defineN 100010intN,m,sd,pd,id[n],sum[n],low[n],dfn[n];BOOLMark[n];stack<int>S;vector<int>Grap[n];voidTarjan (intv) {Low[v]=dfn[v]=++PD; MARK[V]=1;    S.push (v);  for(intI=0; I<grap[v].size (); i++){        intw=Grap[v][i]; if(!Dfn[w])            {Tarjan (w); LOW[V]=min (low[v],low[w]); }        Else if(Mark[w]) {Low[v]=min (low[v],dfn[w]); }    }    intu; if(low[v]==Dfn[v]) {SD++;  Do{u=S.top ();            S.pop (); Id[u]=SD; SUM[SD]++; Mark[u]=0; } while(u!=v); }}intMain () {Freopen ("messagew.in","R", stdin); Freopen ("Messagew.out","W", stdout); scanf ("%d%d",&n,&m);  for(intI=1, x,y;i<=m;i++) scanf ("%d%d",&x,&y), Grap[x].push_back (y);  for(intI=1; i<=n;i++)if(!Dfn[i]) Tarjan (i);  for(intI=1; i<=n;i++) puts (sum[id[i]]>1?"T":"F"); return 0;}

Cojs 1001. [WZOI2011 S3] Message delivery