zoj Peak

​​The 15th Zhejiang Provincial Collegiate Programming Contest Sponsored by TuSimple - A
Peak​​

题意：序列只要满足有一k，即仅存在一个k ，1 < k < n ，a[i] < a[i+1] (1 < i < k ) ; a [ i - 1 ] > a [ i ] ( k < i < n)。
个人理解就是序列先增后减。并且不能连续出现一样的数

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
using namespace std;

int main()
{//序列从大到小再从小到大 
    int T;
    scanf("%d",&T);
    int n;
    while(T--)
    {
        scanf("%d",&n);
        int a[2];
        int flag=0,count=0;

        scanf("%d%d",&a[0],&a[1]);
        if(a[1]>a[0]) flag=1;//先上 

        int stu;//向上 
        if(flag) stu=1;
        else stu=0;

        for(int i=2;i<n;i++)
        {
            scanf("%d",&a[i%2]);
            if(a[i%2]<a[(i-1)%2]&&stu==1)
            count++,stu=0;//向下
            else if(a[i%2]>a[(i-1)%2]&&stu==0)
            count++,stu=1; 

            if(a[i%2]==a[(i-1)%2]) flag=0;
        } 

        //cout<<count<<endl;
        if(flag&&count==1)
        printf("Yes\n");
        else
        printf("No\n");
    }
    return 0;
}