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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4. #define ff(i , a , b) for(int i = a; i <= int(b); i++)
  5. #define REP(i, a , b) for(int i = a; i >= int(b); i--)
  6. #define MP make_pair
  7. #define PB push_back
  8. typedef long long ll;
  9. typedef pair<int ,int> pi;
  10. const ll MAXN = 1e6 + 7;
  11. const int INF = 1e9 + 7;
  12. vector<int> v;
  13. set<int> check;
  14. void solve()
  15. {
  16.     v.clear();
  17.     check.clear();
  18.     int n;
  19.     scanf("%d", &n);
  20.     v.resize(n);
  21.     ff(i , 0 ,n - 1) scanf("%d", &v[i]);
  22.     if (n == 1)
  23.     {
  24.         printf("YES\n");
  25.         return;
  26.     }
  27.     check.insert(v[0]);
  28.     check.insert(INF);
  29.     check.insert(-INF);
  30.     ff(i , 1 , n - 1)
  31.     {
  32.         if (v[i] == v[i-1]) continue;
  33.         if (v[i] > v[i-1])
  34.         {
  35.             auto it = upper_bound(check.begin() , check.end() , v[i-1]);
  36.             if (*it < v[i])
  37.             {
  38.                 printf("NO\n");
  39.                 return;
  40.             }
  41.         }
  42.         if (v[i] < v[i-1])
  43.         {
  44.             auto it = upper_bound(check.begin() , check.end() , v[i]);
  45.             if (*it != v[i-1])
  46.             {
  47.                 printf("NO\n");
  48.                 return;
  49.             }
  50.  
  51.         }
  52.         check.insert(v[i]);
  53.     }
  54.     printf("YES\n");
  55.  
  56. }
  57.  
  58. int main()
  59. {
  60.     //ios_base::sync_with_stdio(0);
  61.     //cin.tie(0);cout.tie(0);
  62.     //freopen("X.inp" , "r" , stdin);
  63.     //freopen("Y.out" , "w" , stdout);
  64.     int t;
  65.     scanf("%d", &t);
  66.     while(t--) solve();
  67.     return 0;
  68. }
  69.  
Success #stdin #stdout 0s 5604KB
comments (?)
stdin 
5
8
-8 2 -6 -5 -4 3 3 2
7
1 1 3 1 0 -2 -1
7
6 12 8 6 2 6 10
6
5 1 2 3 6 7
5
1 3 4 3 0
stdout 
NO
YES
NO
NO
NO
https://ideone.com/xiRkKG
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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