What is a bitonic sequence?

#include <iostream>
using namespace std;
// Helper function to print sequence
void printSequence(int arr[], int n){
    string out = "[";
    for (int i = 0; i < n; i++){
        out+= to_string(arr[i]) + ", ";
    }
    out = out.substr(0, out.length() -2);
    out += "]";
    cout << out << endl;
}
// Finding index of maximum value in an array
int find_maxIndex(int arr[], int n){ 
    int max_index = 0; 
    for (int i = 1; i < n; i++){ 
        if (arr[i] > arr[max_index]){   
            max_index = i; 
        }
    }
    return max_index; 
} 
bool isIncreasingBitonic(int arr[], int low, int high){
    //Base case
    if (high == low){
        return true;
    }
    // Checking for the non increasing pair in array 
    if (arr[high] < arr[high - 1]){
        return false;
    }
    return isIncreasingBitonic(arr, low, high - 1);
}
 
bool isDecreasingBitonic(int arr[], int low, int high){
    // Base case
    if (high == low){
        return true;
    }
    // Checking for the non decreasing in array 
    if (arr[high] > arr[high - 1]){
        return false;
    }
    
    return isDecreasingBitonic(arr, low, high - 1);
}
bool isBitonic(int arr[], int n, int max_index){
    // If array is the increasing bitonic 
    // then the maximum element will be at the last index
    if(max_index == n){
        return isIncreasingBitonic(arr,0,n);
    }
    // If array is the decreasing bitonic 
    // then the maximum element will be at the 0th index
    else if(max_index == 0){
        return isDecreasingBitonic(arr,0,n);
    }
    // If array is first increasing and then decreasing bitonic
    // First check for increasing bitonic till max value
    // Then check for decreasing bitonic from max value till end of array
    else{
        return isIncreasingBitonic(arr,0,max_index) && isDecreasingBitonic(arr,max_index,n);
    }
}
int main(){
    int arr[] = {2, 3, 7, 9, 15, 10, 4};
    int n = sizeof(arr) / sizeof(arr[0]);
    // Finding index for maximum element
    int max_index = find_maxIndex(arr,n);
    //Printing sequence
    cout << "The sequence is: ";
    printSequence(arr, n);
    // Checking if the array is bitonic
    if (isBitonic(arr, n-1, max_index)){
        cout << "This is a bitonic sequence." << endl;
    }
    else{
        cout << "This is not a bitonic sequence." << endl;
    }
    return 0;
}