Find Peak Element – Leetcode Solution

In this post, we are going to solve the 162. Find Peak Element problem of Leetcode. This problem 162. Find Peak Element is a Leetcode medium level problem. Let’s see the code, 162. Find Peak Element – Leetcode Solution.

Problem

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

Given a 0-indexed integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.

You may imagine that nums[-1] = nums[n] = -∞. In other words, an element is always considered to be strictly greater than a neighbor that is outside the array.

You must write an algorithm that runs in O(log n) time.

Example 1 :

Input: nums = [1,2,3,1]
Output: 2
Explanation: 3 is a peak element and your function should return the index number 2.

Example 2 :

Input: nums = [1,2,1,3,5,6,4]
Output: 5
Explanation: Your function can return either index number 1 where the peak element is 2, or index number 5 where the peak element is 6.

Constraints

  • 1 <= nums.length <= 1000
  • -231 <= nums[i] <= 231 - 1
  • nums[i] != nums[i + 1] for all valid i.

Now, let’s see the code of 162. Find Peak Element – Leetcode Solution.

Find Peak Element – Leetcode Solution

162. Find Peak Element – Solution in Java

class Solution {
    public int findPeakElement(int[] nums) {
        int s = 0;
        int e = nums.length-1;

        while(s < e){
            int mid = s - ( s - e)/2;
            int mid2 = mid+1;
            if(nums[mid] < nums[mid2]) {
                s = mid2;
            }else {
                e = mid;
            }
            
        }
        return s;
    }
}

162. Find Peak Element – Solution in C++

class Solution {
public:
    int findPeakElement(vector<int>& nums) {
        int s = 0;
        int e = nums.size()-1;

        while(s < e){
            int mid = s - ( s - e)/2;
            int mid2 = mid+1;
            if(nums[mid] < nums[mid2]) {
                s = mid2;
            }else {
                e = mid;
            }
            
        }
        return s;
    }
};

162. Find Peak Element – Solution in Python

class Solution:
    def findPeakElement(self, nums):
        beg, end = 0, len(nums) - 1
        while beg < end:
            mid = (beg + end)//2
            if nums[mid] < nums[mid + 1]:
                beg = mid + 1
            else:
                end = mid

        return end

Note: This problem 162. Find Peak Element is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.

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