【Codeforces 356A】Knight Tournament

n个人矩形m场比赛每场比赛由编号为li~ri且之前没有被淘汰的人进行。已知第i场的winner是xi winner会把这一场其他所有的人都淘汰。问你n个人每个人都是被谁给淘汰的. 【题解】并查集初始条件f[i] = i,nex[i] = i + 1; 每一轮战斗,让输的人的f[find_father(i)]变成x[i] 但是在执行f[find_father(i)]=x[i]的时候我们要记录一下ans[find_father(i)] = x[i] 因为到最后并查集经过路径压缩以后，就没有明显的主从关系了之后,让li~ri里面的每个nex[i]都等于r[i]+1(要先记录下nex[i]再改变nex[i],因为i需要跳到nex[i],进而继续将li~ri这个区间里面的nex[i]都指向r[i]+1,以及进行合并操作,把对应区间的子winner指向新winner,记录ans值)就好这样从左到右枚举的时候就会跳过败者了(只会通过find_father(i)找到这一棵子树的根) 最后输出ans[]就好注意ans[i]=i的话那个人是最后的winner

【代码】

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

public class Main {
    
    
    static InputReader in;
    static PrintWriter out;
        
    public static void main(String[] args) throws IOException{
        //InputStream ins = new FileInputStream("E:\rush.txt");
        InputStream ins = System.in;
        in = new InputReader(ins);
        out = new PrintWriter(System.out);
        //code start from here
        new Task().solve(in, out);
        out.close();
    }
    
    static int N = (int)3e5;
    static class Task{
        int n,m;
        int nex[],f[],ans[];
        
        int ff(int x) {
        	if (x==f[x]) return x;
        	else {
        		f[x] = ff(f[x]);
        		return f[x];
        	}
        }
        
        public void solve(InputReader in,PrintWriter out) {
        	nex = new int[N+10];f = new int[N+10];ans = new int[N+10];
        	for (int i = 1;i <= N;i++) {
        		nex[i] = i + 1;
        		f[i] = i;
        	}
        	n = in.nextInt();m = in.nextInt();
        	for (int i = 1;i <= m;i++) {
        		int li,ri,xi;
        		li = in.nextInt();ri = in.nextInt();xi = in.nextInt();
        		for (int j = li;j <= ri;) {
        			int fa = ff(j);
        			f[fa] = xi;
        			ans[fa] = xi;
        			int temp = nex[j];
        			nex[j] = ri+1;
        			j = temp;
        		}
        	}
        	for (int i = 1;i <= n;i++) {
        		if (ans[i]==i)
        			out.print(0);
        		else
        			out.print(ans[i]);
        		out.print(" ");
        	}
        }
    }

    

    static class InputReader{
        public BufferedReader br;
        public StringTokenizer tokenizer;
        
        public InputReader(InputStream ins) {
            br = new BufferedReader(new InputStreamReader(ins));
            tokenizer = null;
        }
        
        public String next(){
            while (tokenizer==null || !tokenizer.hasMoreTokens()) {
                try {
                tokenizer = new StringTokenizer(br.readLine());
                }catch(IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
         
        public int nextInt() {
            return Integer.parseInt(next());
        } 
    }
}