Find Peak Element

最新推荐文章于 2020-11-24 11:48:40 发布

Nereus_Li

最新推荐文章于 2020-11-24 11:48:40 发布

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分类专栏： LeetCode

本文链接：https://blog.youkuaiyun.com/li_chihang/article/details/44158553

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本文介绍了一种在不重复遍历数组的情况下找到数组中峰元素（大于其相邻元素的元素）的方法，提供了C++和Python两种实现方式。

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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.

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

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.

C++

 int findPeakElement(const vector<int> &num) {
        for(int i = 1; i < num.size(); i ++)
        {
            if(num[i] < num[i-1])
                return i-1;
        }
        return num.size()-1;
    }

Python

def findPeakElement(self,num):
        if len(num)==1:
            return 0
        for index in range(len(num)):
            if index==0:
                if num[index] > num[index+1] :
                    return index
            elif num[index] < num[index-1]:
                return index-1
        return len(num)-1