代码（样例已过，交上去WA）：

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <limits.h>
#include <cstring>
#include <vector>
using namespace std;

typedef long long LL;
const int INF = 0x3f3f3f3f, INF_BIT = 0x3f;

const int N = 2e6 + 10;

int t;
int n;
int x, y, opt;

struct Node{
    int x, y, opt;
};
vector<Node> add;
vector<int> alls;
int find(int x){
    int l = 0, r = alls.size() - 1;
    while(l <= r){
        int mid = l + (r - l) / 2;
        
        if(x <= alls[mid]) r = mid - 1;
        else l = mid + 1; 
    }
    return r;
}

int fa[N];
int dis[N];
int get(int x){
    if(fa[x] == x) return x;
    else{
        int t = get(fa[x]);
        dis[x] += dis[fa[x]];
        return fa[x] = t;
    }
}

int main(){
    cin >> t;
    while(t--){
        add.clear();
        alls.clear();
        memset(dis, 0, sizeof(dis));
        
        cin >> n;
        for(int i = 1;i <= n;i++){
            cin >> x >> y >> opt;
            
            add.push_back({x, y, opt});
            alls.push_back(x);
            alls.push_back(y);
        }
        
        sort(alls.begin(), alls.end());
        alls.erase(unique(alls.begin(), alls.end()), 
                   alls.end());
        
        for(int i = 1;i <= alls.size();i++){
            fa[i] = i;
        }
        bool flag = true;
        for(int i = 1;i <= n;i++){
            int x = find(add[i].x), y = find(add[i].y), 
                opt = add[i].opt;
            
            if(opt == 0 && add[i].x == add[i].y){
                flag = false;
                break;
            }
            
            int fx = get(x), fy = get(y);
            if(opt == 1){
                if(fx == fy && (dis[x] - dis[y]) % 2){
                    flag = false;
                    break;
                }else{
                    fa[fx] = fy;
                    dis[fx] = dis[y] - dis[x];
                }
            }else if(opt == 0){
                if(fx == fy && (dis[x] - dis[y] - 1) % 2){
                    flag = false;
                    break;
                }else{
                    fa[fx] = fy;
                    dis[fx] = dis[y] + 1 - dis[x];
                }
            }
        }
        
        if(flag) puts("YES");
        else puts("NO");
    }
    return 0;
}

而且我还把第一个数据点下下来：

5
2
1 2 1
1 2 0
3
1 2 1
2 3 1
3 1 1
4
1 2 1
2 3 1
3 4 1
1 4 0
2
1 2 1
2 1 1
1
1 1 1

NO
YES
NO
YES
YES

本地输出正确，但洛谷IDE（linux）上输出错误：

NO
NO
NO
YES
YES

求助：为什么？