[Leetcode] Find Peak Element

Find Peak Element

A peak element is an element, which is greater than its neighbors.

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

The array may be contain multiple peaks, in this case return the index to any one of the peaks is fine.

May imagine 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.

Problem Solving Ideas:

This problem is quite simple, just return one of the peaks. You can scan an array at most once. The authorities say dichotomy, which I think is as efficient as the array is randomly arranged. Pay attention to the handling of special cases.

Class Solution {public:    int findpeakelement (const vector<int> &num) {        int len=num.size ();        Handling Special Cases        if (len==0| | Len==1) {            return 0;        }        if (Num[0]>num[1]) {            return 0;        }        if (Num[len-1]>num[len-2]) {            return len-1;        }        for (int i=1; i<len-1; i++) {            if (num[i]>num[i-1]&&num[i]>num[i+1]) {                return i;            }        }        return 0;}    };

[Leetcode] Find Peak Element