POJ 2492 A Bug's Life

传送门：A Bug's Life

Description

Background

Professor Hopper is researching the sexual behavior of a rare species of bugs. He assumes that they feature two different genders and that they only interact with bugs of the opposite gender. In his experiment, individual bugs and their interactions were easy to identify, because numbers were printed on their backs.         Problem Given a list of bug interactions, decide whether the experiment supports his assumption of two genders with no homosexual bugs or if it contains some bug interactions that falsify it.      

Input

The first line of the input contains the number of scenarios. Each scenario starts with one line giving the number of bugs (at least one, and up to 2000) and the number of interactions (up to 1000000) separated by a single space. In the following lines, each interaction is given in the form of two distinct bug numbers separated by a single space. Bugs are numbered consecutively starting from one.      

Output

The output for every scenario is a line containing "Scenario #i:", where i is the number of the scenario starting at 1, followed by one line saying either "No suspicious bugs found!" if the experiment is consistent with his assumption about the bugs' sexual behavior, or "Suspicious bugs found!" if Professor Hopper's assumption is definitely wrong.      

Sample Input

2
3 3
1 2
2 3
1 3
4 2
1 2
3 4

Sample Output

Scenario #1:
Suspicious bugs found!

Scenario #2:
No suspicious bugs found!

Hint

Huge input,scanf is recommended.

写这道题是为了说明一件重要的事：

不能认为Input总是以EOF结尾。

WA到死的写法（注意加粗的两行）

using namespace std;
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<functional>
#include<vector>
#include<map>
#include<queue>
#include<climits>
#define pq priority_queue
#define X first
#define Y second
#define MP make_pair
#define pb push_back
#define Read(x) freopen(x, "r", stdin)
#define scf(x) scanf(x)
#define prf(x) printf(x)
#define set_0(x) memset(x, 0, sizeof(x))
#define set_1(x) memset(x, -1, sizeof(x));
#define rep(i, l, r) for(int i=l; i<r; i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;

const int MAX_N=2e3+10;
int par[MAX_N];
bool rel[MAX_N];

int find(int x){
  if(par[x]==x) return x;
  int tmp=par[x];
  par[x]=find(par[x]);
  if(rel[x]) rel[x]=rel[tmp];
  else rel[x]=!rel[tmp];
  return par[x];
}

void unite(int x, int y){
  int yy=find(y), xx=find(x);
  if(xx==yy) return;
  par[xx]=yy;
  if(rel[x]==rel[y]) rel[xx]=false;
  else rel[xx]=true;
}

int main(){
  //Read("in");
  scanf("%*d");
  int N, M, a, b, cs=0;
  bool ok;
  while(~scanf("%d%d", &N, &M)){
    for(int i=1; i<=N; i++){
      par[i]=i;
      rel[i]=true; //i与par[i]是否同性
    }
    ok=true;
    while(M--){
      scanf("%d%d", &a, &b);
      if(!ok) continue;
      if(find(a)==find(b)){
        if(rel[a]==rel[b]) ok=false;
      }
      else unite(a, b);
    }
    if(cs) puts("");
    printf("Scenario #%d:
", ++cs);
    puts(ok?"No suspicious bugs found!":"Suspicious bugs found!");
  }
  return 0;
}

AC的姿势：

using namespace std;
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<functional>
#include<vector>
#include<map>
#include<queue>
#include<climits>
#define pq priority_queue
#define X first
#define Y second
#define MP make_pair
#define pb push_back
#define Read(x) freopen(x, "r", stdin)
#define scf(x) scanf(x)
#define prf(x) printf(x)
#define set_0(x) memset(x, 0, sizeof(x))
#define set_1(x) memset(x, -1, sizeof(x));
#define rep(i, l, r) for(int i=l; i<r; i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;

const int MAX_N=2e3+10;
int par[MAX_N];
bool rel[MAX_N];

int find(int x){
  if(par[x]==x) return x;
  int tmp=par[x];
  par[x]=find(par[x]);
  if(rel[x]) rel[x]=rel[tmp];
  else rel[x]=!rel[tmp];
  return par[x];
}

void unite(int x, int y){
  int yy=find(y), xx=find(x);
  if(xx==yy) return;
  par[xx]=yy;
  if(rel[x]==rel[y]) rel[xx]=false;
  else rel[xx]=true;
}

int main(){
  //Read("in");
  int N, M, a, b, cs=0, T;
  bool ok;
  scanf("%d", &T);
  while(T--){
    scanf("%d%d", &N, &M);
    for(int i=1; i<=N; i++){
      par[i]=i;
      rel[i]=true; //i与par[i]是否同性
    }
    ok=true;
    while(M--){
      scanf("%d%d", &a, &b);
      if(!ok) continue;
      if(find(a)==find(b)){
        if(rel[a]==rel[b]) ok=false;
      }
      else unite(a, b);
    }
    if(cs) puts("");
    printf("Scenario #%d:
", ++cs);
    puts(ok?"No suspicious bugs found!":"Suspicious bugs found!");
  }
  return 0;
}