F D01 - Array as a Hill Hackerank Answer

Array of integers is a hill, 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 a hill: [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 a hill.

Input Format

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 ≤ 1000) — the elements of the array.

Output Format

Print "yes" if the given array is a hill. Otherwise, print "no".

Source Code

#include <stdio.h>

#include <string.h>

#include <math.h>

#include <stdlib.h>

int main() {

    int n;

    scanf("%d",&n);

    int a[n];

    for (int i=0;i<n;i++)

    {

        scanf("%d",&a[i]);   

    }

    int i=0;

    while (i<n-1)

    {

        if(a[i]<a[i+1])

            i++;

        else break;

    }

   while (i<n-1)

   {

       if(a[i]==a[i+1])

           i++;

       else break;

   }

   while (i<n-1)

   {

       if(a[i]>a[i+1])

           i++;

       else break;

   }

    if(i==n-1)

        printf("yes");

    else 

        printf("no");

    return 0;

}