C Exercises: Find the index of first peak element in a given array

C Array: Exercise-97 with Solution

Write a program in C to find the index of the first peak element in a given array.

Sample Solution:

C Code:

#include<stdio.h> 
  
int peakElementSearch (int arr1[], int ele_low, int ele_high, int n) 
{ 
    int ele_mid = ele_low + (ele_high - ele_low)/2;  
    if ((ele_mid == 0 || arr1[ele_mid-1] <= arr1[ele_mid]) && (ele_mid == n-1 || arr1[ele_mid+1] <= arr1[ele_mid])) 
        return ele_mid; 
    else if (ele_mid > 0 && arr1[ele_mid-1] > arr1[ele_mid]) 
        return peakElementSearch(arr1, ele_low, (ele_mid -1), n); 
    else return peakElementSearch(arr1, (ele_mid + 1), ele_high, n); 
} 
int PeakFinding(int arr1[], int n) 
{ 
    return peakElementSearch(arr1, 0, n-1, n); 
} 
  
int main() 
{ 
    int arr1[] = {5, 12, 13, 20, 16, 19, 11, 7, 25}; 
    int n = sizeof(arr1)/sizeof(arr1[0]);
    int i = 0; 
   //------------- print original array ------------------	
	printf("The given array is:  \n");
	for(i = 0; i < n; i++)
		{
			printf("%d  ", arr1[i]);
		}
	printf("\n");
//-----------------------------------------------------------  	
    printf("The index of first peak element in the array is: %d", PeakFinding(arr1, n)); 
    return 0; 
} 

Sample Output:

The given array is:  
5  12  13  20  16  19  11  7  25  
The index of first peak element in the array is: 3

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Flowchart:

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