Program to check bitnoicity of an array in C++

Given an array arr[N] of N integers, the task is to check whether the given array is bitonic or not. If the given array is bitonic then print “Yes its a bitonic array”, else print “No its not a bitonic array”.

A Bitonic array is when the array is in strictly increasing order first and then in strictly decreasing order.

Like this array arr[] = {1, 2, 3, 4, 2, -1, -5} is a bitonic array, because till 4 it is in strictly increasing order and after 4 it is in strictly decreasing order.

Input

arr[] = {1, 3, 5, 4, 2, 0}

Output

Yes its a bitonic array

Explanation

1< 3 < 5 > 4 > 2 >0, so yes it is a bitonic array.

Input

arr[] = {1, 2, 3, 4, 5, 0, -1, -2, 6, -4}

Output

No its not a bitonic array

Approach used below is as follows to solve the problem

Iterate every element of an array and check that the previous element is smaller than the current element.
When the previous element is not smaller than the current element break.
Check if the previous element is larger than the current, else return false and exit.
If reached the end of an array return true.

Algorithm

Start
Step 1→ Declare array to check for bitonicity of an array
   int check(int arr[], int size)
      declare int i, j
      Loop For i = 1 and i <size and i++
         IF (arr[i] > arr[i - 1])
            Continue
         End
         IF (arr[i] <= arr[i - 1])
            break
         End
         IF(i == size - 1)
            return 1
         End
         Loop For (j = i + 1 and j < size and j++
            IF (arr[j] < arr[j - 1])
               Continue
            End
            IF (arr[j] <= arr[j - 1])
               break
            End
         End
         Set i = j
         IF (i != size)
            return 0
         End
         return 1
Step 2→ In main()
   Declare int arr[] = { -3, 9, 11, 20, 17, 5, 1 }
   Declare int size = sizeof(arr) / sizeof(arr[0])
   Do (check(arr, size) == 1) ? cout << "Yes its a bitonic array" : cout << "no its not a bitonic array"
Stop

Example

Live Demo

#include <bits/stdc++.h>
using namespace std;
//function to check bitonic or not
int check(int arr[], int size){
   int i, j;
   for (i = 1; i < size; i++){
      if (arr[i] > arr[i - 1])
         continue;
      if (arr[i] <= arr[i - 1])
         break;
   }
   if (i == size - 1)
      return 1;
   for (j = i + 1; j < size; j++){
      if (arr[j] < arr[j - 1])
         continue;
      if (arr[j] >= arr[j - 1])
         break;
   }
   i = j;
   if (i != size)
      return 0;
   return 1;
}
int main(){
   int arr[] = { -3, 9, 11, 20, 17, 5, 1 };
   int size = sizeof(arr) / sizeof(arr[0]);
   (check(arr, size) == 1) ? cout << "Yes its a bitonic array" : cout << "no its not a bitonic array";
   return 0;
}