HIHO #1121 : 二分图一•二分图判定

#include<bits/stdc++.h>
using namespace std;
#define cl(a,b) memset(a,b,sizeof(a))
#define LL long long
#define pb push_back
#define gcd __gcd

#define For(i,j,k) for(int i=(j);i<k;i++)
#define lowbit(i) (i&(-i))
#define _(x) printf("%d\n",x)

const int maxn = 1e6+10;
const int inf  = 1 << 28;

vector<int> G[maxn];
int color[maxn];

void init(){
for(int i=0;i<maxn;i++){
G[i].clear();
color[i]=0;
}
}

bool dfs(int u){
for(int i=0;i<G[u].size();i++){
int v = G[u][i];
if(color[v]==color[u])return false;
if(!color[v]){
color[v] = 3 - color[u];
if(!dfs(v))return false;
}
}
return true;
}

bool work(int n){
for(int i=1;i<=n;i++){
if(color[i]==0){
color[i]=1;
if(!dfs(i))return false;
}
}
return true;
}
int main(){
int T;scanf("%d",&T);
while(T--){
int n,m;
scanf("%d%d",&n,&m);
init();
for(int i=0;i<m;i++){
int x,y;scanf("%d%d",&x,&y);
G[x].pb(y);
G[y].pb(x);
}
printf("%s\n",work(n)?"Correct":"Wrong");
}
return 0;
}