CCC14S3题解

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

public class CCC14S3{
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException  e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }

    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        for(int jj = 0 ; jj < N ;jj++){
            Stack <Integer> top = new Stack();
            Stack <Integer> branch = new Stack<>();
            int a = sc.nextInt();
            for(int i =0 ; i < a ; i ++){
                top.add(sc.nextInt());
            }
            int goal = 1;
            boolean ans = true;
            while(true){
                if(top.empty()){
                    if(branch.empty())break;
                    if(branch.peek() != goal){
                        ans = false;
                        break;
                    }else{
                        branch.pop();
                        goal ++;
                    }
                }else{
                    if(top.peek() == goal){
                        top.pop();
                        goal ++;
                    }else if(!branch.empty() && branch.peek() == goal){
                        branch.pop();
                        goal ++;
                    }else{
                        branch.push(top.pop());
                    }
                }
            }
            System.out.println(ans?"Y":"N");
        }
    }
}