Binary Search LeetCode Problems: All 253,
With Python Solutions

Every problem in this library that LeetCode tags Binary Search. 213 of them carry a complete Python solution, a worked example and the time and space complexity of the approach.

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Easy: 30
Medium: 138
Hard: 85

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How Binary Search problems are solved

A tag names the subject, not the method. These pattern hubs cover the techniques that actually solve Binary Search problems — each one explains the approach, gives a Python template and states its complexity.

Binary SearchHalve the search space each step — over an array, or over the answer itself.

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python

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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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python

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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+

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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

Primary display

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

Binary Search problems by difficulty

Showing the first 200 of 253 problems. Problems with a complete Python solution are listed first, then by ascending problem number.

Easy (24)

Easy problems
No.	Problem	Topics
0035	Search Insert Position	Array, Binary Search
0069	Sqrt(x)	Math, Binary Search
0222	Count Complete Tree Nodes	Bit Manipulation, Tree, Binary Search +1
0268	Missing Number	Bit Manipulation, Array, Hash Table +3
0278	First Bad Version	Binary Search, Interactive
0349	Intersection of Two Arrays	Array, Hash Table, Two Pointers +2
0350	Intersection of Two Arrays II	Array, Hash Table, Two Pointers +2
0367	Valid Perfect Square	Math, Binary Search
0374	Guess Number Higher or Lower	Binary Search, Interactive
0441	Arranging Coins	Math, Binary Search
0704	Binary Search	Array, Binary Search
0744	Find Smallest Letter Greater Than Target	Array, Binary Search
0888	Fair Candy Swap	Array, Hash Table, Binary Search +1
1337	The K Weakest Rows in a Matrix	Array, Binary Search, Matrix +2
1346	Check If N and Its Double Exist	Array, Hash Table, Two Pointers +2
1351	Count Negative Numbers in a Sorted Matrix	Array, Binary Search, Matrix
1385	Find the Distance Value Between Two Arrays	Array, Two Pointers, Binary Search +1
1539	Kth Missing Positive Number	Array, Binary Search
1608	Special Array With X Elements Greater Than or Equal X	Array, Binary Search, Sorting
2089	Find Target Indices After Sorting Array	Array, Binary Search, Sorting
2389	Longest Subsequence With Limited Sum	Greedy, Array, Binary Search +2
2529	Maximum Count of Positive Integer and Negative Integer	Array, Binary Search, Counting
2540	Minimum Common Value	Array, Hash Table, Two Pointers +1
2824	Count Pairs Whose Sum is Less than Target	Array, Two Pointers, Binary Search +1

Medium (108)

Medium problems
No.	Problem	Topics
0033	Search in Rotated Sorted Array	Array, Binary Search
0034	Find First and Last Position of Element in Sorted Array	Array, Binary Search
0074	Search a 2D Matrix	Array, Binary Search, Matrix
0081	Search in Rotated Sorted Array II	Array, Binary Search
0153	Find Minimum in Rotated Sorted Array	Array, Binary Search
0162	Find Peak Element	Array, Binary Search
0167	Two Sum II - Input Array Is Sorted	Array, Two Pointers, Binary Search
0209	Minimum Size Subarray Sum	Array, Binary Search, Prefix Sum +1
0240	Search a 2D Matrix II	Array, Binary Search, Divide and Conquer +1
0275	H-Index II	Array, Binary Search
0287	Find the Duplicate Number	Bit Manipulation, Array, Two Pointers +1
0300	Longest Increasing Subsequence	Array, Binary Search, Dynamic Programming
0378	Kth Smallest Element in a Sorted Matrix	Array, Binary Search, Matrix +2
0400	Nth Digit	Math, Binary Search
0436	Find Right Interval	Array, Binary Search, Sorting
0456	132 Pattern	Stack, Array, Binary Search +2
0475	Heaters	Array, Two Pointers, Binary Search +1
0497	Random Point in Non-overlapping Rectangles	Reservoir Sampling, Array, Math +4
0528	Random Pick with Weight	Array, Math, Binary Search +2
0532	K-diff Pairs in an Array	Array, Hash Table, Two Pointers +2
0540	Single Element in a Sorted Array	Array, Binary Search
0611	Valid Triangle Number	Greedy, Array, Two Pointers +2
0633	Sum of Square Numbers	Math, Two Pointers, Binary Search
0658	Find K Closest Elements	Array, Two Pointers, Binary Search +3
0713	Subarray Product Less Than K	Array, Binary Search, Prefix Sum +1
0718	Maximum Length of Repeated Subarray	Array, Binary Search, Dynamic Programming +3
0729	My Calendar I	Design, Segment Tree, Array +2
0731	My Calendar II	Design, Segment Tree, Array +3
0754	Reach a Number	Math, Binary Search
0786	K-th Smallest Prime Fraction	Array, Two Pointers, Binary Search +2
0792	Number of Matching Subsequences	Trie, Array, Hash Table +4
0825	Friends Of Appropriate Ages	Array, Two Pointers, Binary Search +1
0826	Most Profit Assigning Work	Greedy, Array, Two Pointers +2
0852	Peak Index in a Mountain Array	Array, Binary Search
0875	Koko Eating Bananas	Array, Binary Search
0911	Online Election	Design, Array, Hash Table +1
0981	Time Based Key-Value Store	Design, Hash Table, String +1
1004	Max Consecutive Ones III	Array, Binary Search, Prefix Sum +1
1011	Capacity To Ship Packages Within D Days	Array, Binary Search
1027	Longest Arithmetic Subsequence	Array, Hash Table, Binary Search +1
1146	Snapshot Array	Design, Array, Hash Table +1
1170	Compare Strings by Frequency of the Smallest Character	Array, Hash Table, String +2
1201	Ugly Number III	Math, Binary Search, Combinatorics +1
1208	Get Equal Substrings Within Budget	String, Binary Search, Prefix Sum +1
1237	Find Positive Integer Solution for a Given Equation	Math, Two Pointers, Binary Search +1
1268	Search Suggestions System	Trie, Array, String +3
1283	Find the Smallest Divisor Given a Threshold	Array, Binary Search
1292	Maximum Side Length of a Square with Sum Less than or Equal to Threshold	Array, Binary Search, Matrix +1
1300	Sum of Mutated Array Closest to Target	Array, Binary Search, Sorting
1348	Tweet Counts Per Frequency	Design, Hash Table, String +3
1477	Find Two Non-overlapping Sub-arrays Each With Target Sum	Array, Hash Table, Binary Search +2
1482	Minimum Number of Days to Make m Bouquets	Array, Binary Search
1488	Avoid Flood in The City	Greedy, Array, Hash Table +2
1498	Number of Subsequences That Satisfy the Given Sum Condition	Array, Two Pointers, Binary Search +1
1508	Range Sum of Sorted Subarray Sums	Array, Two Pointers, Binary Search +2
1552	Magnetic Force Between Two Balls	Array, Binary Search, Sorting
1562	Find Latest Group of Size M	Array, Hash Table, Binary Search +1
1574	Shortest Subarray to be Removed to Make Array Sorted	Stack, Array, Two Pointers +2
1631	Path With Minimum Effort	Depth-First Search, Breadth-First Search, Union Find +4
1648	Sell Diminishing-Valued Colored Balls	Greedy, Array, Math +3
1658	Minimum Operations to Reduce X to Zero	Array, Hash Table, Binary Search +2
1712	Ways to Split Array Into Three Subarrays	Array, Two Pointers, Binary Search +1
1760	Minimum Limit of Balls in a Bag	Array, Binary Search
1802	Maximum Value at a Given Index in a Bounded Array	Greedy, Math, Binary Search
1818	Minimum Absolute Sum Difference	Array, Binary Search, Ordered Set +1
1838	Frequency of the Most Frequent Element	Greedy, Array, Binary Search +3
1855	Maximum Distance Between a Pair of Values	Array, Two Pointers, Binary Search
1870	Minimum Speed to Arrive on Time	Array, Binary Search
1894	Find the Student that Will Replace the Chalk	Array, Binary Search, Prefix Sum +1
1898	Maximum Number of Removable Characters	Array, Two Pointers, String +1
1901	Find a Peak Element II	Array, Binary Search, Matrix
1954	Minimum Garden Perimeter to Collect Enough Apples	Math, Binary Search
2008	Maximum Earnings From Taxi	Array, Hash Table, Binary Search +2
2024	Maximize the Confusion of an Exam	String, Binary Search, Prefix Sum +1
2054	Two Best Non-Overlapping Events	Array, Binary Search, Dynamic Programming +2
2055	Plates Between Candles	Array, String, Binary Search +1
2064	Minimized Maximum of Products Distributed to Any Store	Greedy, Array, Binary Search
2070	Most Beautiful Item for Each Query	Array, Binary Search, Sorting
2080	Range Frequency Queries	Design, Segment Tree, Array +2
2187	Minimum Time to Complete Trips	Array, Binary Search
2226	Maximum Candies Allocated to K Children	Array, Binary Search
2250	Count Number of Rectangles Containing Each Point	Binary Indexed Tree, Array, Hash Table +2
2271	Maximum White Tiles Covered by a Carpet	Greedy, Array, Binary Search +3
2300	Successful Pairs of Spells and Potions	Array, Two Pointers, Binary Search +1
2332	The Latest Time to Catch a Bus	Array, Two Pointers, Binary Search +1
2333	Minimum Sum of Squared Difference	Greedy, Array, Binary Search +2
2358	Maximum Number of Groups Entering a Competition	Greedy, Array, Math +1
2411	Smallest Subarrays With Maximum Bitwise OR	Bit Manipulation, Array, Binary Search +1
2424	Longest Uploaded Prefix	Union Find, Design, Binary Indexed Tree +5
2439	Minimize Maximum of Array	Greedy, Array, Binary Search +2
2476	Closest Nodes Queries in a Binary Search Tree	Tree, Depth-First Search, Binary Search Tree +3
2498	Frog Jump II	Greedy, Array, Binary Search
2501	Longest Square Streak in an Array	Array, Hash Table, Binary Search +2
2513	Minimize the Maximum of Two Arrays	Math, Binary Search, Number Theory
2517	Maximum Tastiness of Candy Basket	Greedy, Array, Binary Search +1
2554	Maximum Number of Integers to Choose From a Range I	Greedy, Array, Hash Table +2
2555	Maximize Win From Two Segments	Array, Binary Search, Sliding Window
2560	House Robber IV	Greedy, Array, Binary Search +1
2563	Count the Number of Fair Pairs	Array, Two Pointers, Binary Search +1
2576	Find the Maximum Number of Marked Indices	Greedy, Array, Two Pointers +2
2594	Minimum Time to Repair Cars	Array, Binary Search
2601	Prime Subtraction Operation	Greedy, Array, Math +2
2602	Minimum Operations to Make All Array Elements Equal	Array, Binary Search, Prefix Sum +1
2616	Minimize the Maximum Difference of Pairs	Greedy, Array, Binary Search +2
2779	Maximum Beauty of an Array After Applying Operation	Array, Binary Search, Sorting +1
2812	Find the Safest Path in a Grid	Breadth-First Search, Union Find, Array +3
2817	Minimum Absolute Difference Between Elements With Constraint	Array, Binary Search, Ordered Set
2826	Sorting Three Groups	Array, Binary Search, Dynamic Programming

Hard (68)

Hard problems
No.	Problem	Topics
0004	Median of Two Sorted Arrays	Array, Binary Search, Divide and Conquer
0154	Find Minimum in Rotated Sorted Array II	Array, Binary Search
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
0354	Russian Doll Envelopes	Array, Binary Search, Dynamic Programming +1
0363	Max Sum of Rectangle No Larger Than K	Array, Binary Search, Matrix +2
0410	Split Array Largest Sum	Greedy, Array, Binary Search +2
0483	Smallest Good Base	Math, Binary Search
0493	Reverse Pairs	Binary Indexed Tree, Segment Tree, Array +4
0668	Kth Smallest Number in Multiplication Table	Math, Binary Search
0710	Random Pick with Blacklist	Array, Hash Table, Math +3
0719	Find K-th Smallest Pair Distance	Array, Two Pointers, Binary Search +1
0732	My Calendar III	Design, Segment Tree, Binary Search +2
0778	Swim in Rising Water	Depth-First Search, Breadth-First Search, Union Find +4
0793	Preimage Size of Factorial Zeroes Function	Math, Binary Search
0862	Shortest Subarray with Sum at Least K	Queue, Array, Binary Search +4
0878	Nth Magical Number	Math, Binary Search
0887	Super Egg Drop	Math, Binary Search, Dynamic Programming
0902	Numbers At Most N Given Digit Set	Array, Math, String +2
1044	Longest Duplicate Substring	String, Binary Search, Suffix Array +3
1095	Find in Mountain Array	Array, Binary Search, Interactive
1157	Online Majority Element In Subarray	Design, Binary Indexed Tree, Segment Tree +2
1187	Make Array Strictly Increasing	Array, Binary Search, Dynamic Programming +1
1235	Maximum Profit in Job Scheduling	Array, Binary Search, Dynamic Programming +1
1439	Find the Kth Smallest Sum of a Matrix With Sorted Rows	Array, Binary Search, Matrix +1
1483	Kth Ancestor of a Tree Node	Bit Manipulation, Tree, Depth-First Search +4
1521	Find a Value of a Mysterious Function Closest to Target	Bit Manipulation, Segment Tree, Array +1
1649	Create Sorted Array through Instructions	Binary Indexed Tree, Segment Tree, Array +4
1671	Minimum Number of Removals to Make Mountain Array	Greedy, Array, Binary Search +1
1713	Minimum Operations to Make a Subsequence	Greedy, Array, Hash Table +1
1739	Building Boxes	Greedy, Math, Binary Search
1751	Maximum Number of Events That Can Be Attended II	Array, Binary Search, Dynamic Programming +1
1782	Count Pairs Of Nodes	Graph, Array, Hash Table +4
1793	Maximum Score of a Good Subarray	Stack, Array, Two Pointers +2
1847	Closest Room	Array, Binary Search, Ordered Set +1
1851	Minimum Interval to Include Each Query	Array, Binary Search, Sorting +2
1862	Sum of Floored Pairs	Array, Math, Binary Search +1
1889	Minimum Space Wasted From Packaging	Array, Binary Search, Prefix Sum +1
1923	Longest Common Subpath	Array, Binary Search, Suffix Array +2
1964	Find the Longest Valid Obstacle Course at Each Position	Binary Indexed Tree, Array, Binary Search
1970	Last Day Where You Can Still Cross	Depth-First Search, Breadth-First Search, Union Find +3
2009	Minimum Number of Operations to Make Array Continuous	Array, Hash Table, Binary Search +1
2035	Partition Array Into Two Arrays to Minimize Sum Difference	Bit Manipulation, Array, Two Pointers +4
2040	Kth Smallest Product of Two Sorted Arrays	Array, Binary Search
2071	Maximum Number of Tasks You Can Assign	Greedy, Queue, Array +4
2106	Maximum Fruits Harvested After at Most K Steps	Array, Binary Search, Prefix Sum +1
2111	Minimum Operations to Make the Array K-Increasing	Array, Binary Search
2141	Maximum Running Time of N Computers	Greedy, Array, Binary Search +1
2179	Count Good Triplets in an Array	Binary Indexed Tree, Segment Tree, Array +4
2234	Maximum Total Beauty of the Gardens	Greedy, Array, Two Pointers +4
2251	Number of Flowers in Full Bloom	Array, Hash Table, Binary Search +3
2258	Escape the Spreading Fire	Breadth-First Search, Array, Binary Search +1
2286	Booking Concert Tickets in Groups	Design, Binary Indexed Tree, Segment Tree +1
2302	Count Subarrays With Score Less Than K	Array, Binary Search, Prefix Sum +1
2354	Number of Excellent Pairs	Bit Manipulation, Array, Hash Table +1
2398	Maximum Number of Robots Within Budget	Queue, Array, Binary Search +4
2426	Number of Pairs Satisfying Inequality	Binary Indexed Tree, Segment Tree, Array +4
2448	Minimum Cost to Make Array Equal	Greedy, Array, Binary Search +2
2454	Next Greater Element IV	Stack, Array, Binary Search +3
2468	Split Message Based on Limit	String, Binary Search, Enumeration
2528	Maximize the Minimum Powered City	Greedy, Queue, Array +3
2565	Subsequence With the Minimum Score	Two Pointers, String, Binary Search
2589	Minimum Time to Complete All Tasks	Stack, Greedy, 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
2736	Maximum Sum Queries	Stack, Binary Indexed Tree, Segment Tree +4
2790	Maximum Number of Groups With Increasing Length	Greedy, Array, Math +2

How Binary Search problems are solved

When the Binary Search problem arrives live.

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Binary Search problems by difficulty

Easy (24)24

Medium (108)108

Hard (68)68

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Easy (24)

Medium (108)

Hard (68)