Find a Peak Element in an Array | LeetCode 162 | Programming Tutorials

Given an array of integers, find a peak element. The array may contain multiple peak elements, in that case return any one peak element.

A peak element is an element which is greater than it's neighbours.

In this tutorial, I have discussed how we can find a peak element using linear scan and a binary search using java code.

Interview questions on an array -

[ProgrammingTutorialsM]

Code link is present in the description box.

[arunks]

Will it work in this case array = [1, 2, 1, 4, 5, 6, 7, 8, 9, 10], here the peak is 2, but the above code logic will fail.

[sureshpathak]

But if it is not sorted order then it will not work i.e binary search

[PRiyankaSingh-nddn]

Great Explaination!
Could you please explain why does exactly your code works and not this with the minor change which seems equivalent to your code:

class Solution {
public int findPeakElement(int[] nums) {
int l=0, h=nums.length-1;

while(l<=h) {
int m= l+(h-l)/2;
if((m==0 || nums[m-1]<nums[m]) && (m==nums.length-1 || nums[m]>nums[m+1]))
return m;
else if(m>0 && nums[m-1]<nums[m])
l=m+1;
else h=m-1;
}
return -1;
}
}

[seydaozdemir]

if we use this array:
int [ ] arr= {2, 3, 4, 7, 5, 10, 3};
then peak is not 10, still 7