## FIRST PEAK ELEMENT in java

An element is called a peak element if its value is not smaller than the value of its adjacent elements(if they exists). Given an array arr[] of size n, find the index of first peak element. If peak element does not exist print -1.

### Input

line 1: contains an integer n denoting size of array.

line 2: contains n spaced integers denoting elements of array.

### Output

Print a single integer denoting the index of first peak element in array. If no such element exists, print -1.

### Constraints

1<=n<=10^6

1<=arr[i]<=10^6

Expected Time Complexity: O(N)

Expected Space Complexity: O(1)

### Sample Input

``````3
1 2 3
``````

### Sample Output

``2``

## Solution of FIRST PEAK ELEMENT :–

``````import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
public static void main (String[] args) throws java.lang.Exception
{
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int arr[] = new int[n];
int temp=-1;

for(int i=0;i<n;i++)
{
arr[i]=sc.nextInt();
}

for(int i=0;i<n;i++)
{

if(i==0)
{
if(arr[i]>arr[i+1])
{
temp=i;
break;
}
}
else if(i==n-1)
{
if(arr[i]>arr[i-1])
{
temp=i;
break;
}
}
else{
if(arr[i]>arr[i-1] && arr[i]>arr[i+1])
{
temp=i;
break;
}
}
}
System.out.println(temp);
}
}``````