****雨露霜雪，雪霜露雨

道理白秋月学长已经说明白，直接上代码

参考代码（python）

from sys import stdin,setrecursionlimit
from math import inf,ceil,sqrt
from collections import Counter,deque

for _ in range(int(stdin.readline())):
    n=int(stdin.readline())
    a=[int(_) for _ in stdin.readline().split()]
    v=['0' for _ in range(n)]
    mn=a[0]
    mx=a[n-1]
    v[0]='1'
    v[n-1]='1'
    for i in range(n):
        if a[i]<=mn:
            mn=a[i]
            v[i]='1'
        if a[n-i-1]>=mx:
            mx=a[n-i-1]
            v[n-i-1]='1'
    print(''.join(v))