UESTC 电子科大专题训练 数据结构 J

#include "iostream"
#include "string.h"
#include "stack"
#include "queue"
#include "string"
#include "vector"
#include "set"
#include "map"
#include "algorithm"
#include "stdio.h"
#include "math.h"
#define ll long long
#define bug(x) cout<<x<<" "<<"UUUUU"<<endl;
#define mem(a) memset(a,0,sizeof(a))
#define mp(x,y) make_pair(x,y)
#define pb(x) push_back(x)
using namespace std;
const long long INF = 1e18+1LL;
const int inf = 1e9+1e8;
const int N=1e6+100;
const ll mod=1e9+7;

int n,m,pre[N];
void init(int n){
    for(int i=0; i<=n; ++i) pre[i]=i;
}
int finds(int x){
    return pre[x]=pre[x]==x?x:finds(pre[x]);
}
void unions(int x, int y){
    int fx=finds(x), fy=finds(y);
    pre[fy]=fx;
}
int main(){
    ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    cin>>n>>m;
    init(2*n);
    int t,a,b;
    for(int i=1; i<=m; ++i){
        cin>>t>>a>>b;
        if(t==1){
            unions(a, b);
            unions(a+n, b+n);
        }
        else{
            unions(a, b+n);
            unions(b, a+n);
        }
    }
    for(int i=1; i<=n; ++i){
        int fi=finds(i), fn=finds(i+n);
        if(fi==fn){
            cout<<"NO\n";
            return 0;
        }
    }
    cout<<"YES\n";
    return 0;
}