(Easy) Peak Index in a Mountain Array (LeetCode)

Description:

Let's call an array A a mountain if the following properties hold:

• A.length >= 3
• There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]

Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].

Example 1:

Input: [0,1,0]
Output: 1

Example 2:

Input: [0,2,1,0]
Output: 1

Note:

1. 3 <= A.length <= 10000
2. 0 <= A[i] <= 10^6
3. A is a mountain, as defined above.

 

Solution:

class Solution {
    public int peakIndexInMountainArray(int[] A) {
        
        if(A==null||A.length==0){
            return 0;
        }
        
        int index = 0;
        for(int i = 0; i<A.length-1; i++){
            
            
            if(A[i]>A[i+1]){
                
                index = i; 
                break;
            }
        }
        
        return index;
        
    }
}