How hard is LeetCode 2951. Find the Peaks?

LeetCode 2951. Find the Peaks is rated Easy on LeetCode.

What is the time complexity of LeetCode 2951. Find the Peaks?

The Python solution on this page runs in O(n), where n is the length of the array.

What is the space complexity of LeetCode 2951. Find the Peaks?

The Python solution on this page uses O(1) auxiliary space.

What topics does LeetCode 2951. Find the Peaks cover?

LeetCode 2951. Find the Peaks is tagged Array and Enumeration on LeetCode.

EasyNo. 2951

Find the Peaks — LeetCode 2951 Python Solution

Topics: Array, Enumeration
Reading time: 2 min
Source: leetcode.com

The problem

You are given a 0-indexed array mountain. Your task is to find all the peaks in the mountain array.

Example

Input: mountain = [2,4,4]
Output: []
Explanation: mountain[0] and mountain[2] can not be a peak because they are first and last elements of the array.

Python solution

PythonSolution

class Solution:
    def findPeaks(self, mountain: List[int]) -> List[int]:
        return [
            i
            for i in range(1, len(mountain) - 1)
            if mountain[i - 1] < mountain[i] > mountain[i + 1]
        ]

Complexity

Time: O(n)where n is the length of the array
Space · auxiliary: O(1)

Related problems
No.	Problem	Difficulty
1534	Count Good Triplets	Easy
1566	Detect Pattern of Length M Repeated K or More Times	Easy
1620	Coordinate With Maximum Network Quality	Medium
2735	Collecting Chocolates	Medium
2765	Longest Alternating Subarray	Easy
2778	Sum of Squares of Special Elements	Easy

Frequently asked questions

How hard is LeetCode 2951. Find the Peaks?: LeetCode 2951. Find the Peaks is rated Easy on LeetCode.
What is the time complexity of LeetCode 2951. Find the Peaks?: The Python solution on this page runs in O(n), where n is the length of the array.
What is the space complexity of LeetCode 2951. Find the Peaks?: The Python solution on this page uses O(1) auxiliary space.
What topics does LeetCode 2951. Find the Peaks cover?: LeetCode 2951. Find the Peaks is tagged Array and Enumeration on LeetCode.

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python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

Technical interview · 45 minsolution.pyShared editor · Python 3Longest substring without repeatsMediumGiven a string s, return the length of the longest contiguous substring in which every character is unique.s = "abcabcbb"
→ 31def length_of_longest_substring(s: str) -> int:2 last_seen = {}3 left = best = 04 for right, ch in enumerate(s):5 if ch in last_seen and last_seen[ch] >= left:

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

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Transcribing...

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python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 TerraClear chat

Transcribing...

QuitEscHide+QCapture+PCrop+OSubmit+EnterPress to get answerLeft/Right+Up/Down+

90%Subscription

python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

python

def length_of_longest_substring(s: str) -> int:    last_seen = {}                    # char -> index    left = best = 0    for right, ch in enumerate(s):        if ch in last_seen and last_seen[ch] >= left:            left = last_seen[ch] + 1  # jump past it        last_seen[ch] = right        best = max(best, right - left + 1)    return best    last_seen = {}                    # char -> index

Approach

At each index r, the window's left edge is:

left r = max (left r -1, last[s r] + 1)

Time O(n): each character enters and leaves the window once.
Space O(min(n, k)): k is the size of the character set.

Type your message...

GPT-6.1 TerraClear chat

Transcribing...

Primary display

QuitEscHide+QCapture+PCrop+OSubmit+EnterPress to get answerLeft/Right+Up/Down+

The problem

Example

Python solution

Complexity

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