Problem:
Score : 300 points

Problem Statement

You are given an array A of length N.
Your task is to divide it into several contiguous subarrays.
Here, all subarrays obtained must be sorted in either non-decreasing or non-increasing order.
At least how many subarrays do you need to divide A into?

Constraints

1 \leq N \leq 10^5

1 \leq A_i \leq 10^9

Each A_i is an integer.

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the minimum possible number of subarrays after division of A.

Sample Input 1

6
1 2 3 2 2 1

Sample Output 1

2

One optimal solution is to divide the array into [1,2,3] and [2,2,1].

Sample Input 2

9
1 2 1 2 1 2 1 2 1

Sample Output 2

5

Sample Input 3

7
1 2 3 2 1 999999999 1000000000

Sample Output 3

3

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int f(int a ,int b){
  if(a < b){
    return 1;
  }

  else if(a > b){
    return -1;
  }

  else{
    return 0;
  }
}

int main(void){
  int n;
  scanf("%d",&n);

  int a[n];
  for(int i = 0;i < n;i ++){
    scanf("%d",&a[i]);
  }

  int flag , count = 0;
  flag = f(a[0],a[1]);

  for(int i = 0;i < n-1;i ++){
    if(a[i] < a[i+1]){
      if(flag == -1){
        count ++;
        i ++;
        flag = f(a[i],a[i+1]);
      }
      else if(flag == 0){
        flag = 1;
      }
    }

    else if(a[i] > a[i+1]){
      if(flag == 1){
        count ++;
        i ++;
        flag = f(a[i],a[i+1]);
      }
      else if(flag == 0){
        flag = -1;
      }
    }
  }

  if(flag == 1){
    if(a[n-2] < a[n-1]){
      count ++;
    }
  }

  else if(flag == -1){
    if(a[n-2] > a[n-1]){
      count ++;
    }
  }

  printf("%d\n",count);

  return 0;
}