Ordered Set LeetCode Problems: All 57,
With Python Solutions

Every problem in this library that LeetCode tags Ordered Set. 47 of them carry a complete Python solution, a worked example and the time and space complexity of the approach.

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Easy: 1
Medium: 20
Hard: 36

Ordered Set problems by difficulty

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

Easy (1)

Easy problems
No.	Problem	Topics
2363	Merge Similar Items	Array, Hash Table, Ordered Set +1

Medium (20)

Medium problems
No.	Problem	Topics
0456	132 Pattern	Stack, Array, Binary Search +2
0497	Random Point in Non-overlapping Rectangles	Reservoir Sampling, Array, Math +4
0729	My Calendar I	Design, Segment Tree, Array +2
0731	My Calendar II	Design, Segment Tree, Array +3
0855	Exam Room	Design, Ordered Set, Heap (Priority Queue)
1348	Tweet Counts Per Frequency	Design, Hash Table, String +3
1418	Display Table of Food Orders in a Restaurant	Array, Hash Table, String +2
1438	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	Queue, Array, Ordered Set +3
1818	Minimum Absolute Sum Difference	Array, Binary Search, Ordered Set +1
2034	Stock Price Fluctuation	Design, Hash Table, Data Stream +2
2336	Smallest Number in Infinite Set	Design, Hash Table, Ordered Set +1
2349	Design a Number Container System	Design, Hash Table, Ordered Set +1
2353	Design a Food Rating System	Design, Array, Hash Table +3
2424	Longest Uploaded Prefix	Union Find, Design, Binary Indexed Tree +5
2762	Continuous Subarrays	Queue, Array, Ordered Set +3
2817	Minimum Absolute Difference Between Elements With Constraint	Array, Binary Search, Ordered Set
0635	Design Log Storage SystemPremium	Design, Hash Table, String +1
1902	Depth of BST Given Insertion OrderPremium	Tree, Binary Search Tree, Array +2
2021	Brightest Position on StreetPremium	Array, Ordered Set, Prefix Sum +1
2031	Count Subarrays With More Ones Than ZerosPremium	Binary Indexed Tree, Segment Tree, Array +5

Hard (36)

Hard problems
No.	Problem	Topics
0218	The Skyline Problem	Binary Indexed Tree, Segment Tree, Array +5
0220	Contains Duplicate III	Array, Bucket Sort, Ordered Set +2
0315	Count of Smaller Numbers After Self	Binary Indexed Tree, Segment Tree, Array +4
0327	Count of Range Sum	Binary Indexed Tree, Segment Tree, Array +4
0352	Data Stream as Disjoint Intervals	Union Find, Design, Hash Table +3
0363	Max Sum of Rectangle No Larger Than K	Array, Binary Search, Matrix +2
0493	Reverse Pairs	Binary Indexed Tree, Segment Tree, Array +4
0699	Falling Squares	Segment Tree, Array, Ordered Set
0715	Range Module	Design, Segment Tree, Ordered Set
0732	My Calendar III	Design, Segment Tree, Binary Search +2
0850	Rectangle Area II	Segment Tree, Array, Ordered Set +1
0895	Maximum Frequency Stack	Stack, Design, Hash Table +1
0975	Odd Even Jump	Stack, Array, Dynamic Programming +3
1606	Find Servers That Handled Most Number of Requests	Array, Ordered Set, Simulation +1
1649	Create Sorted Array through Instructions	Binary Indexed Tree, Segment Tree, Array +4
1675	Minimize Deviation in Array	Greedy, Array, Ordered Set +1
1825	Finding MK Average	Design, Queue, Data Stream +2
1847	Closest Room	Array, Binary Search, Ordered Set +1
1912	Design Movie Rental System	Design, Array, Hash Table +2
2035	Partition Array Into Two Arrays to Minimize Sum Difference	Bit Manipulation, Array, Two Pointers +4
2102	Sequentially Ordinal Rank Tracker	Design, Data Stream, Ordered Set +1
2179	Count Good Triplets in an Array	Binary Indexed Tree, Segment Tree, Array +4
2213	Longest Substring of One Repeating Character	Segment Tree, Array, String +1
2251	Number of Flowers in Full Bloom	Array, Hash Table, Binary Search +3
2276	Count Integers in Intervals	Design, Segment Tree, Ordered Set
2382	Maximum Segment Sum After Removals	Union Find, Array, Ordered Set +1
2426	Number of Pairs Satisfying Inequality	Binary Indexed Tree, Segment Tree, Array +4
2612	Minimum Reverse Operations	Breadth-First Search, Union Find, Array +2
2659	Make Array Empty	Greedy, Binary Indexed Tree, Segment Tree +4
2713	Maximum Strictly Increasing Cells in a Matrix	Memoization, Array, Hash Table +5
0683	K Empty SlotsPremium	Binary Indexed Tree, Segment Tree, Queue +5
0716	Max StackPremium	Stack, Design, Linked List +2
2158	Amount of New Area Painted Each DayPremium	Segment Tree, Array, Ordered Set
2254	Design Video Sharing PlatformPremium	Stack, Design, Hash Table +1
2519	Count the Number of K-Big IndicesPremium	Binary Indexed Tree, Segment Tree, Array +4
2613	Beautiful PairsPremium	Geometry, Array, Math +3

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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.

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.

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

Primary display

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

Ordered Set problems by difficulty

Easy (1)1

Medium (20)20

Hard (36)36

When the Ordered Set problem arrives live.

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Easy (1)

Medium (20)

Hard (36)