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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
  5. #define int long long
  6. #define rep(i,a,b) for(int i=a;i<b;++i)
  7. #define yes cout << "YES\n"
  8. #define no cout << "NO\n"
  9.  
  10. void solve() {
  11.     int n; cin >> n;
  12.     int* a = new int[n];
  13.     rep(i, 0, n) cin >> a[i];
  14.  
  15.     int i = 0;
  16.     while (i + 1 < n && a[i] <= a[i + 1]) ++i;
  17.  
  18.     // allow all-equal case
  19.     bool all_equal = true;
  20.     rep(j, 1, n) {
  21.         if (a[j] != a[0]) {
  22.             all_equal = false;
  23.             break;
  24.         }
  25.     }
  26.  
  27.     if (!all_equal && (i == 0 || i == n - 1)) {
  28.         no;
  29.         delete[] a;
  30.         return;
  31.     }
  32.  
  33.     while (i + 1 < n && a[i] >= a[i + 1]) ++i;
  34.  
  35.     if (i == n - 1) yes;
  36.     else no;
  37.  
  38.     delete[] a;
  39. }
  40.  
  41. int32_t main() {
  42.     fast_io;
  43.     int t; cin >> t;
  44.     while (t--) solve();
  45.     return 0;
  46. }
  47.  
Success #stdin #stdout 0.01s 5320KB
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stdin
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4
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5 6 1 1
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40 60 90
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stdout
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YES
NO
NO
YES
https://ideone.com/uOYUkW
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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