How hard is LeetCode 2475. Number of Unequal Triplets in Array?

LeetCode 2475. Number of Unequal Triplets in Array is rated Easy on LeetCode.

What is the time complexity of LeetCode 2475. Number of Unequal Triplets in Array?

The Python solution on this page runs in O(n^3), where n is the length of the array nums.

What is the space complexity of LeetCode 2475. Number of Unequal Triplets in Array?

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

What topics does LeetCode 2475. Number of Unequal Triplets in Array cover?

LeetCode 2475. Number of Unequal Triplets in Array is tagged Array, Hash Table and Sorting on LeetCode.

EasyNo. 2475

Number of Unequal Triplets in Array — LeetCode 2475 Python Solution

Pattern: Sorting
Topics: Array, Hash Table, Sorting
Reading time: 2 min
Source: leetcode.com

The problem

You are given a 0-indexed array of positive integers nums. Find the number of triplets (i, j, k) that meet the following conditions: 0 <= i < j < k < nums.length nums[i], nums[j], and nums[k] are pairwise distinct.

Example

Input: nums = [4,4,2,4,3]
Output: 3
Explanation: The following triplets meet the conditions:

Python solution

PythonSolution

class Solution:
    def unequalTriplets(self, nums: List[int]) -> int:
        n = len(nums)
        ans = 0
        for i in range(n):
            for j in range(i + 1, n):
                for k in range(j + 1, n):
                    ans += (
                        nums[i] != nums[j] and nums[j] != nums[k] and nums[i] != nums[k]
                    )
        return ans

Complexity

Time: O(n3)where n is the length of the array nums
Space · auxiliary: O(1)

Pattern: Sorting

Spend O(n log n) once to buy an ordering that makes the rest of the problem trivial. LeetCode 2475. Number of Unequal Triplets in Array is filed here because LeetCode tags it Sorting, which is the vocabulary this hub collects.

The sorting guide has the Python template for the pattern and the 401 LeetCode problems that use it.

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0217	Contains Duplicate	Easy
0229	Majority Element II	Medium
0268	Missing Number	Easy

Frequently asked questions

How hard is LeetCode 2475. Number of Unequal Triplets in Array?: LeetCode 2475. Number of Unequal Triplets in Array is rated Easy on LeetCode.
What is the time complexity of LeetCode 2475. Number of Unequal Triplets in Array?: The Python solution on this page runs in O(n³), where n is the length of the array nums.
What is the space complexity of LeetCode 2475. Number of Unequal Triplets in Array?: The Python solution on this page uses O(1) auxiliary space.
What topics does LeetCode 2475. Number of Unequal Triplets in Array cover?: LeetCode 2475. Number of Unequal Triplets in Array is tagged Array, Hash Table and Sorting 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.

Type your message...

GPT-6.1 Terra

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

Pattern: Sorting

Related problems

Frequently asked questions

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Approach

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