JavaScript LeetCode Problems: 67 Python Solutions

JavaScript problems by difficulty

Problems with a complete Python solution are listed first, then by ascending problem number.

Easy (30)

Easy problems
No.	Problem	Topics
2619	Array Prototype Last	JavaScript
2620	Counter	JavaScript
2621	Sleep	JavaScript
2626	Array Reduce Transformation	JavaScript
2629	Function Composition	JavaScript
2634	Filter Elements from Array	JavaScript
2635	Apply Transform Over Each Element in Array	JavaScript
2648	Generate Fibonacci Sequence	JavaScript
2665	Counter II	JavaScript
2666	Allow One Function Call	JavaScript
2667	Create Hello World Function	JavaScript
2677	Chunk Array	JavaScript
2690	Infinite Method ObjectPremium	JavaScript
2695	Array Wrapper	JavaScript
2703	Return Length of Arguments Passed	JavaScript
2704	To Be Or Not To Be	JavaScript
2715	Timeout Cancellation	JavaScript
2723	Add Two Promises	JavaScript
2724	Sort By	JavaScript
2725	Interval Cancellation	JavaScript
2726	Calculator with Method Chaining	JavaScript
2727	Is Object Empty	JavaScript
2758	Next DayPremium	JavaScript
2774	Array Upper BoundPremium	JavaScript
2794	Create Object from Two ArraysPremium	JavaScript
2796	Repeat StringPremium	JavaScript
2797	Partial Function with PlaceholdersPremium	JavaScript
2803	Factorial GeneratorPremium	JavaScript
2804	Array Prototype ForEachPremium	JavaScript
2822	Inversion of ObjectPremium	JavaScript

Medium (31)

Medium problems
No.	Problem	Topics
2618	Check if Object Instance of Class	JavaScript
2622	Cache With Time Limit	JavaScript
2623	Memoize	JavaScript
2624	Snail Traversal	JavaScript
2625	Flatten Deeply Nested Array	JavaScript
2627	Debounce	JavaScript
2628	JSON Deep EqualPremium	JavaScript
2631	Group By	JavaScript
2632	CurryPremium	JavaScript
2633	Convert Object to JSON StringPremium	JavaScript
2636	Promise PoolPremium	JavaScript
2637	Promise Time Limit	JavaScript
2649	Nested Array Generator	JavaScript
2676	ThrottlePremium	JavaScript
2692	Make Object ImmutablePremium	JavaScript
2693	Call Function with Custom Context	JavaScript
2694	Event Emitter	JavaScript
2700	Differences Between Two ObjectsPremium	JavaScript
2705	Compact Object	JavaScript
2721	Execute Asynchronous Functions in Parallel	JavaScript
2722	Join Two Arrays by ID	JavaScript
2754	Bind Function to ContextPremium	JavaScript
2755	Deep Merge of Two ObjectsPremium	JavaScript
2757	Generate Circular Array ValuesPremium	JavaScript
2775	Undefined to NullPremium	JavaScript
2776	Convert Callback Based Function to Promise Based FunctionPremium	JavaScript
2777	Date Range GeneratorPremium	JavaScript
2795	Parallel Execution of Promises for Individual Results RetrievalPremium	JavaScript
2805	Custom IntervalPremium	JavaScript
2821	Delay the Resolution of Each PromisePremium	JavaScript
2823	Deep Object FilterPremium	JavaScript

Hard (6)

Hard problems
No.	Problem	Topics
2630	Memoize II	JavaScript
2650	Design Cancellable Function	JavaScript
2675	Array of Objects to MatrixPremium	JavaScript
2691	Immutability HelperPremium	JavaScript
2756	Query BatchingPremium	JavaScript
2759	Convert JSON String to ObjectPremium	JavaScript

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python

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

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

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python

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

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 TerraClear chat

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.

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...

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

JavaScript LeetCode Problems: All 67,
With Python Solutions

JavaScript problems by difficulty

Easy (30)

Medium (31)

Hard (6)

When the JavaScript problem arrives live.

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JavaScript problems by difficulty

Easy (30)30

Medium (31)31

Hard (6)6

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Keep exploring

Easy (30)

Medium (31)

Hard (6)