[NOI2015] 程序自动分析

代码

#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
inline int read(){
    int x=0,f=1;char c=getchar();
    while ('0'>c||c>'9') {if (c=='-') f=-1;c=getchar();}
    while ('0'<=c&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar();
    return x*f;
}
const int maxn(1e6+5);
int n,flag;
int f[maxn];
int cnt;
struct node{
    int x,y,z;
    bool operator < (const node& x) const{
        return z>x.z;
    }
}e[maxn];
int b[maxn*3];
inline int find(int x){
    return f[x]==x?x:f[x]=find(f[x]);
}

void init(){
    n=read();
    memset(e,0,sizeof(e));
    memset(b,0,sizeof(b));
    memset(f,0,sizeof(f));
    flag=1;
    cnt=0;
    for (int i(1);i<=n;++i){
        e[i].x=read(),e[i].y=read(),e[i].z=read();
        b[++cnt]=e[i].x;
        b[++cnt]=e[i].y;
    }
    sort(b+1,b+cnt+1);
    cnt=unique(b+1,b+cnt+1)-b-1;
    for (int i(1);i<=n;++i){
        e[i].x=lower_bound(b,b+cnt,e[i].x)-b;
        e[i].y=lower_bound(b,b+cnt,e[i].y)-b;
    }
    for (int i(1);i<=cnt;++i) f[i]=i;
    sort(e+1,e+1+n);
}

void doit(){
    for (int i(1);i<=n;++i){
        int x=find(e[i].x),y=find(e[i].y);
        if (e[i].z) f[x]=y;
        else if (x==y){
            puts("NO");
            flag=0;
            break;
        }
    }
    if (flag) puts("YES");
}

int main(){
    int t=read();
    while (t--){
        init();
        doit();
    }
    return 0;
}