题目描述

思路

  • 首先这个题目判断顺序不会影响最终答案，可以先判断所有等式，再判断所有不等式，只要有不等式不成立那就是错误。（相等：在同一集合，不相等：在不同集合）
  • 因为数据范围是1E9，会超过限制内存。我们需要做一个哈希来映射。

代码

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import java.io.*;
import java.util.*;

class Main{
    public static int N = 100010,P = N*2 - 1;
    public static Option[] os = new Option[N];
    public static int[] hash = new int[N*2],find = new int[N*2];
    public static Scanner sc = new Scanner(System.in);
    
    public static int get(int x){
        int k = x % P;
        for(int i = k;i < N * 2 - 1;i ++){
            if(hash[i] == -1 || hash[i] == x)
                return i;
        }
        return -1;
    }
    
    public static int find(int x){
        if(find[x] != x) find[x] = find(find[x]);
        return find[x];
    }
    
    public static void main(String[] args){
        int k = sc.nextInt();
        while((k--)!=0){
            for(int i = 1;i < N*2;i++) find[i] = i;
            Arrays.fill(hash,-1);
            int n = sc.nextInt();
            for(int i = 1;i <= n;i++){
                int x1 = sc.nextInt(),x2 = sc.nextInt(),o = sc.nextInt();
                os[i] = new Option(x1,x2,o);
            }
            
            //等号条件都加进去
            
            for(int i = 1;i <= n;i++){
                if(os[i].o == 1)
                {
                    int x1 = os[i].x1,x2 = os[i].x2;
                    int a = get(x1),b = get(x2);
                    hash[a] = x1;
                    hash[b] = x2;
                    int pa = find(a),pb = find(b);
                    if(pa != pb) find[pa] = pb;
                    
                }
            }
            
            int index = 0;
            //判断不等号
            for(int i = 1;i <= n;i++){
                if(os[i].o == 0){
                    int x1 = os[i].x1,x2 = os[i].x2;
                    int a = get(x1),b = get(x2);
                    int pa = find(a),pb = find(b);
                    if(pa == pb){
                        index = 1;
                        System.out.println("NO");
                        break;
                    }
                }
            }
            
            if(index == 0) System.out.println("YES");
        }
    }
    
    
    static class Option{
        int x1,x2,o;
        public Option(int x1,int x2,int o){
            this.x1 = x1;
            this.x2 = x2;
            this.o = o;
        }
        
    }
}