Zigzag

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <utility>
#include <set>

typedef long long LL;

using namespace std;

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n; cin >> n;
    vector<int> v;
    for(int i = 0; i < n; i++){
        int x; cin >> x; v.push_back(x);
    }
    
    if(n == 1){
        cout << 1 << endl;
        return 0;
    }
    if(n == 2){
        if(v[0] == v[1]) cout << 1 << endl;
        else cout << 2 << endl;
        return 0;
    }
    
    LL ans = 0;
    LL first = -1; LL last = -1;
    for(int i = 1; i < n-1; i++){
        if(!(v[i-1] <= v[i] && v[i] <= v[i+1]) &&
           !(v[i-1] >= v[i] && v[i] >= v[i+1])){
            ans++;
            if(first == -1) first = i;
            last = i;
        }
    }
    
    if(first == -1 || v[0] != v[first]) ans++;
    if(last == -1 || v[n-1] != v[last]) ans++;
    cout << ans << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: ACCEPTED

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: WRONG ANSWER