Solution: Peak Element

#include<iostream>
using namespace std;
/* Function to find the peak element in the array */
int findPeak(int arr[], int n){
  if(n==1)     // Handling the edge case (if the array is of size 1)
    return -1;
  for(int i = 1; i<n-1; i++){
    if(arr[i] >= arr[i-1] && arr[i] >= arr[i+1])
      return i;
  }
  if(arr[0] >= arr[1])
    return 0;
    
  if(arr[n-1] >= arr[n-2])
    return n-1;
}
/* Driver program to check above functions */
int main() {
  int arr[] = {7,11,22,13,4,0};
  int x = sizeof(arr);
  int y = sizeof(arr[0]);
  int arrSize = x / y;
  cout << "One peak point index is: " << findPeak(arr, arrSize) << endl;
}

#include <iostream>
using namespace std;
// The function below is based on the recursive binary search algorithm
// It returns the index of the peak element in the given array
int findPeakRecursive(int low, int high, int size, int array[]) {
  // Just as in binary search, we will first find the middle element 
  int middle = low + (high - low) / 2;
  // If neighbors of the middle element exist, compare them with the element 
  if ((middle == size - 1 || array[middle + 1] <= array[middle]) &&
  		(middle == 0 || array[middle - 1] <= array[middle]))
  		return middle;
  // If the left neighbor of the middle element is greater
  // The peak element must be in the left subarray
  else if (array[middle - 1] > array[middle] && middle > 0)
  		return findPeakRecursive(low, (middle - 1), size, array);
  // If the right neighbor of the middle element is greater
  // The peak element must be in the right subarray
  else 
    	return findPeakRecursive((middle + 1), high, size, array);
}
// Wrapper to call the recursive findPeakRecursive() 
int findPeak(int arr[], int n) {
  return findPeakRecursive(0, n - 1, n, arr);
}
/* Driver program to check above functions */
int main() {
  int arr[] = {7,11,22,13,4,0};
  int x = sizeof(arr);
  int y = sizeof(arr[0]);
  int arrSize = x / y;
  cout << "One peak point index is: " << findPeak(arr, arrSize) << endl;
}