B. Beautiful Numbers

Topic: https://codeforces.com/contest/1265/problem/B

After seeing the title, I want complicated, but if you want to clear, very simple

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 const int N=2e5+5;
 4 int pos[N];
 5 int main()
 6 {
 7     int n,t;
 8     scanf("%d",&t);
 9     while(t--)
10     {
11         scanf("%d",&n);
12         int num;
13         for(int i=1;i<=n;i++)
14         {
15             scanf("%d",&num);
16             pos[num]=i;
17         }
18         int l=pos[1],r=pos[1];
19         for(int i=1;i<=n;i++)
20         {
21             l=min(pos[i],l);
22             r=max(pos[i],r);
23             if(r-l+1==i)
24                 printf("1");
25             else
26                 printf("0");
27         }
28         printf("\n");
29     }
30     return 0;
31 }