?昨晚的沒來得及打,最近錯過好幾場CF了,這場應該不算太難
Array of integers is?unimodal, if:
- it is strictly increasing in the beginning;
- after that it is constant;
- after that it is strictly decreasing.
The first block (increasing) and the last block (decreasing) may be absent. It is allowed that both of this blocks are absent.
For example, the following three arrays are unimodal:?[5,?7,?11,?11,?2,?1],?[4,?4,?2],?[7], but the following three are not unimodal:?[5,?5,?6,?6,?1],?[1,?2,?1,?2],?[4,?5,?5,?6].
Write a program that checks if an array is unimodal.
The first line contains integer?n?(1?≤?n?≤?100) — the number of elements in the array.
The second line contains?n?integers?a1,?a2,?...,?an?(1?≤?ai?≤?1?000) — the elements of the array.
Print "YES" if the given array is unimodal. Otherwise, print "NO".
You can output each letter in any case (upper or lower).
6
1 5 5 5 4 2
YES
5
10 20 30 20 10
YES
4
1 2 1 2
NO
7
3 3 3 3 3 3 3
YES
In the first example the array is unimodal, because it is strictly increasing in the beginning (from position?1?to position?2, inclusively), that it is constant (from position?2?to position?4, inclusively) and then it is strictly decreasing (from position?4?to position?6, inclusively).
這個A可能比B還要難一點,給你一個序列,滿足左側嚴格遞增,中間相等,右側嚴格遞減,左右也可以為空,你判定下
#include <bits/stdc++.h> using namespace std; int main() {int n;int a[105];cin>>n;for(int i=1; i<=n; i++)cin>>a[i];int f1=1;a[n+1]=a[0]=1<<30;int f=2;while(a[f]>a[f-1]) f++;while(a[f]==a[f-1]) f++;while(a[f]<a[f-1]) f++;if(f<=n) cout<<"NO"<<endl;else cout<<"YES"<<endl;return 0; }