https://leetcode.com/problems/find-peak-element/

find-peak-element.java

class Solution {
    public int findPeakElement(int[] nums) {
        int l = 0;
        int r = nums.length - 1;
        
        while(l < r) {
            int mid = l + (r - l)  / 2;
            int next = mid + 1; // safe to use mid + 1
            if (nums[mid] < nums[next]) {
                l = mid + 1;
            } else {
                r = mid;
            }
        }
        return l;
    }
}