• Round #424 A. Unimodal Array


    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.

    Input

    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.

    Output

    Print "YES" if the given array is unimodal. Otherwise, print "NO".

    You can output each letter in any case (upper or lower).

    Examples
    input
    6
    1 5 5 5 4 2
    output
    YES
    input
    5
    10 20 30 20 10
    output
    YES
    input
    4
    1 2 1 2
    output
    NO
    input
    7
    3 3 3 3 3 3 3
    output
    YES
    Note

    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).

     1 /*
     2 题目大意:有一个序列
     3 如果满足左部严格上升(可以为空),中间恒定,右部严格下降(可以为空)
     4 那么就输出YES,否则输出NO
     5 解题思路:按照规则走一遍,如果没走完,那么就NO,否则YES。
     6 */
     7 #include <iostream>
     8 using namespace std;
     9 const int MAXN=105;
    10 const int INF=0x3f3f3f3f;
    11 int a[MAXN];
    12 int main(){
    13     int n;
    14     while(cin>>n){
    15         for(int i=1;i<=n;i++)
    16             cin>>a[i];
    17         a[n+1]=INF;
    18         int p=2;
    19         while(a[p]>a[p-1]) p++;
    20         while(a [p]==a[p-1]) p++;
    21         while(a[p]<a[p-1])  p++;
    22         if(p<=n) cout<<"NO"<<endl;
    23         else cout<<"YES"<<endl;
    24     }
    25     return 0;
    26 }
     1 #include <iostream>
     2 #define N 105
     3 using namespace std;
     4 int n,maxn=1,a[N];
     5 bool check(){
     6     for(int i=1;i<=n;i++){
     7         if(a[i]==maxn){
     8             for(int j=i-1;j>=1;j--)
     9                 if(a[j]>=a[j+1]) return false;
    10             while(a[i]==maxn&&i<=n)
    11                 i++;
    12             for(int j=i;j<=n;j++)
    13                 if(a[j-1]<=a[j]||a[j]>=maxn)
    14                 return false;
    15             break;
    16         }
    17     }
    18     return true;
    19 }
    20 int main(){
    21     cin>>n;
    22     for(int i=1;i<=n;i++)
    23         cin>>a[i],maxn=max(a[i],maxn);
    24     if(check())
    25         cout<<"YES"<<endl;
    26     else cout<<"NO"<<endl;
    27     return 0;
    28 }
  • 相关阅读:
    linux三剑客之grep
    MySQL练习(1)
    appium获取toast方法
    Could not parse UiSelector argument: 'XXX' is not a string 错误解决办法
    基于python的几种排序算法的实现
    生成allure测试报告之后,服务器端口无法访问查看生成的report,可能是这样引起的。
    通过源码看原理之 selenium
    如何查看浏览器记住的密码
    传智播客JavaWeb day09-mysql入门、数据库操作、数据库表操作、数据行操作
    SQLServer数据库表架构和数据保存成sql文件
  • 原文地址:https://www.cnblogs.com/z-712/p/7307935.html
Copyright © 2020-2023  润新知