[LeetCode] Find Peak Element

A peak element is an element that is greater than its neighbors.

Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.

You may imagine that num[-1] = num[n] = -∞.

For example, in array [1, 2, 3, 1], 3 is a peak element and your function should return the index number 2.

    public int findPeakElement(int[] num) {        return find(num, 0, num.length-1);    }    public int find(int[] num, int start, int end) {        int mid = (start + end)/2;        if ( (mid == 0 || num[mid] > num[mid-1]) && (mid == num.length-1 || num[mid] > num[mid+1])) return mid;        else if (mid > 0 && num[mid-1] > num[mid]) return find(num, start, mid-1);        else return find(num, mid + 1, end);    }