Leetcode#162Find Peak Element

Find Peak Element

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Question Solution 

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.

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Credits:
Special thanks to @ts for adding this problem and creating all test cases.

分析：遍历数据，找波峰，即某一个大于相邻的点的点

public class Solution {

    public int findPeakElement(int[] nums) {

        int l=nums.length;

        if(l==0)

            return -1;

        else if(l==1)

            return 0;

        else

        {

            if(nums[0]>nums[1])

                return 0;

            if(nums[l-1]>nums[l-2])

                return l-1;

            

            for(int i=1;i<l-1;i++)

                if(nums[i]>nums[i-1]&&nums[i]>nums[i+1])

                    return i;

        }  

        return -1;

    }

}