Educational Codeforces Round 32 A. Local Extrema（模拟水题）

Love The Way You Lie 2022-06-06 13:25 166阅读 0赞

A. Local Extrema

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

You are given an array *a*. Some element of this array *a**i* is a *local minimum* iff it is strictly less than both of its neighbours (that is, *a**i* < *a**i* - 1and *a**i* < *a**i* + 1). Also the element can be called *local maximum* iff it is strictly greater than its neighbours (that is, *a**i* > *a**i* - 1 and *a**i* > *a**i* + 1). Since *a*1 and *a**n* have only one neighbour each, they are neither local minima nor local maxima.

An element is called a *local extremum* iff it is either local maximum or local minimum. Your task is to calculate the number of local extrema in the given array.

Input

The first line contains one integer *n* (1 ≤ *n* ≤ 1000) — the number of elements in array *a*.

The second line contains *n* integers *a*1, *a*2, ..., *a**n* (1 ≤ *a**i* ≤ 1000) — the elements of array *a*.

Output

Print the number of local extrema in the given array.

Examples

input

3
    1 2 3

output

input

4
    1 5 2 5

output

题解：

今晚心血来潮打了一场cf，水几发博客hhhh，这题太水了不说

代码：

#include<string.h>
    #include<stdlib.h>
    #include<queue>
    #include<stack>
    #include<math.h>
    #include<vector>
    #include<map>
    #include<set>
    #include<stdlib.h>
    #include<cmath>
    #include<string>
    #include<algorithm>
    #include<iostream>
    using namespace std;
    #define lson k*2
    #define rson k*2+1
    #define M (t[k].l+t[k].r)/2
    #define ll long long
    int main()
    {
        int n,i,j,ans=0;
        int a[1005];
        scanf("%d",&n);
        for(i=0;i<n;i++)
            scanf("%d",&a[i]);
        for(i=1;i<n-1;i++)
        {
            if(a[i-1]>a[i]&&a[i+1]>a[i]||a[i-1]<a[i]&&a[i+1]<a[i])
                ans++;
        }
        printf("%d\n",ans);
    	return 0;
    }