Codeforces Round #424 A（模拟）

 #include<cstdio>
 int n,a[];
 int main(){
     scanf("%d",&n);
     for(int i=;i<=n;++i)scanf("%d",a+i);
     int L=,R=n;
     while(L<n&&a[L]<a[L+])++L;
     while(R>&&a[R]<a[R-])--R;
     for(int i=L+;i<=R;++i)if(a[L]!=a[i])return puts("NO"),;
     return puts("YES"),;
 }

 #include <iostream>
 using namespace std;
 int N;
 int V[];
 int main()
 {
     cin>>N;
     for(int i=;i<=N;i++)cin>>V[i];
     int i=;
     while(i<N&&V[i]<V[i+])i++;
     while(i<N&&V[i]==V[i+])i++;
     while(i<N&&V[i]>V[i+])i++;
     if(i<N)cout<<"NO";
     else cout<<"YES";
     return ;
 }

 #include<iostream>
 #include<cstdio>
 using namespace std;
 int n;
 int a[];
 int main()
 {
     scanf("%d",&n);
     for(int i=;i<=n;i++)scanf("%d",a+i);
     int i=;
     while(i+<=n && a[i+]>a[i])i++;
     while(i+<=n && a[i+]==a[i])i++;
     while(i+<=n && a[i+]<a[i])i++;
     if(i<n)printf("NO");else printf("YES");
     return ;
 } 

 #include<bits/stdc++.h>
 using namespace std;

 int main()
 {
     int n;
     cin>>n;
     int arr[n];
     for(int i=;i<n;i++)
         cin>>arr[i];
     int i=;
     while(arr[i+]>arr[i] && i+<n)
         i++;
     while(arr[i]==arr[i+] && i+<n)
         i++;
     while(arr[i]>arr[i+] && i+<n)
         i++;
     if(i==n-)
         cout<<"YES";
     else cout<<"NO";

 }

 #include <bits/stdc++.h>

 using namespace std;

 int a[];
 int n;
 void sol(string s) {
     cout << s;
     exit();
 }
 int main() {
 #ifndef ONLINE_JUDGE
     freopen("CF.in", "r", stdin);
 #endif
     cin >> n;
     for (int i = ; i <= n; ++i)cin >> a[i];
     int i=;
     while(i+<=n&&a[i]<a[i+])++i;
     while(i+<=n&&a[i]==a[i+])++i;
     while(i+<=n)
     {
         if(a[i]<=a[i+])sol("NO");
         ++i;
     }sol("YES");
 }