Simulation LeetCode Problems: All 144,
With Python Solutions

Every problem in this library that LeetCode tags Simulation. 132 of them carry a complete Python solution, a worked example and the time and space complexity of the approach.

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Easy: 57
Medium: 77
Hard: 10

Simulation problems by difficulty

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

Easy (57)

Easy problems
No.	Problem	Topics
0067	Add Binary	Bit Manipulation, Math, String +1
0258	Add Digits	Math, Number Theory, Simulation
0412	Fizz Buzz	Math, String, Simulation
0415	Add Strings	Math, String, Simulation
0495	Teemo Attacking	Array, Simulation
0566	Reshape the Matrix	Array, Matrix, Simulation
0657	Robot Return to Origin	String, Simulation
0682	Baseball Game	Stack, Array, Simulation
0832	Flipping an Image	Bit Manipulation, Array, Two Pointers +2
0844	Backspace String Compare	Stack, Two Pointers, String +1
0867	Transpose Matrix	Array, Matrix, Simulation
0999	Available Captures for Rook	Array, Matrix, Simulation
1103	Distribute Candies to People	Math, Simulation
1252	Cells with Odd Values in a Matrix	Array, Math, Simulation
1260	Shift 2D Grid	Array, Matrix, Simulation
1275	Find Winner on a Tic Tac Toe Game	Array, Hash Table, Matrix +1
1389	Create Target Array in the Given Order	Array, Simulation
1518	Water Bottles	Math, Simulation
1560	Most Visited Sector in a Circular Track	Array, Simulation
1603	Design Parking System	Design, Counting, Simulation
1646	Get Maximum in Generated Array	Array, Simulation
1688	Count of Matches in Tournament	Math, Simulation
1700	Number of Students Unable to Eat Lunch	Stack, Queue, Array +1
1920	Build Array from Permutation	Array, Simulation
1929	Concatenation of Array	Array, Simulation
1945	Sum of Digits of String After Convert	String, Simulation
2011	Final Value of Variable After Performing Operations	Array, String, Simulation
2022	Convert 1D Array Into 2D Array	Array, Matrix, Simulation
2073	Time Needed to Buy Tickets	Queue, Array, Simulation
2138	Divide a String Into Groups of Size k	String, Simulation
2154	Keep Multiplying Found Values by Two	Array, Hash Table, Sorting +1
2169	Count Operations to Obtain Zero	Math, Simulation
2180	Count Integers With Even Digit Sum	Math, Simulation
2243	Calculate Digit Sum of a String	String, Simulation
2293	Min Max Game	Array, Simulation
2303	Calculate Amount Paid in Taxes	Array, Simulation
2357	Make Array Zero by Subtracting Equal Amounts	Greedy, Array, Hash Table +3
2460	Apply Operations to an Array	Array, Two Pointers, Simulation
2500	Delete Greatest Value in Each Row	Array, Matrix, Sorting +2
2549	Count Distinct Numbers on Board	Array, Hash Table, Math +1
2553	Separate the Digits in an Array	Array, Simulation
2558	Take Gifts From the Richest Pile	Array, Simulation, Heap (Priority Queue)
2562	Find the Array Concatenation Value	Array, Two Pointers, Simulation
2582	Pass the Pillow	Math, Simulation
2660	Determine the Winner of a Bowling Game	Array, Simulation
2682	Find the Losers of the Circular Game	Array, Hash Table, Simulation
2696	Minimum String Length After Removing Substrings	Stack, String, Simulation
2717	Semi-Ordered Permutation	Array, Simulation
2739	Total Distance Traveled	Math, Simulation
2744	Find Maximum Number of String Pairs	Array, Hash Table, String +1
2810	Faulty Keyboard	String, Simulation
2899	Last Visited Integers	Array, Simulation
2946	Matrix Similarity After Cyclic Shifts	Array, Math, Matrix +1
2960	Count Tested Devices After Test Operations	Array, Counting, Simulation
2974	Minimum Number Game	Array, Sorting, Simulation +1
0157	Read N Characters Given Read4Premium	Array, Interactive, Simulation
1243	Array TransformationPremium	Array, Simulation

Medium (77)

Medium problems
No.	Problem	Topics
0043	Multiply Strings	Math, String, Simulation
0054	Spiral Matrix	Array, Matrix, Simulation
0059	Spiral Matrix II	Array, Matrix, Simulation
0289	Game of Life	Array, Matrix, Simulation
0498	Diagonal Traverse	Array, Matrix, Simulation
0537	Complex Number Multiplication	Math, String, Simulation
0592	Fraction Addition and Subtraction	Math, String, Simulation
0640	Solve the Equation	Math, String, Simulation
0735	Asteroid Collision	Stack, Array, Simulation
0874	Walking Robot Simulation	Array, Hash Table, Simulation
0885	Spiral Matrix III	Array, Matrix, Simulation
0946	Validate Stack Sequences	Stack, Array, Simulation
0950	Reveal Cards In Increasing Order	Queue, Array, Sorting +1
0985	Sum of Even Numbers After Queries	Array, Simulation
1006	Clumsy Factorial	Stack, Math, Simulation
1041	Robot Bounded In Circle	Math, String, Simulation
1094	Car Pooling	Array, Prefix Sum, Sorting +2
1222	Queens That Can Attack the King	Array, Matrix, Simulation
1324	Print Words Vertically	Array, String, Simulation
1404	Number of Steps to Reduce a Number in Binary Representation to One	Bit Manipulation, String, Simulation
1409	Queries on a Permutation With Key	Binary Indexed Tree, Array, Simulation
1441	Build an Array With Stack Operations	Stack, Array, Simulation
1503	Last Moment Before All Ants Fall Out of a Plank	Brainteaser, Array, Simulation
1535	Find the Winner of an Array Game	Array, Simulation
1545	Find Kth Bit in Nth Binary String	Recursion, String, Simulation
1562	Find Latest Group of Size M	Array, Hash Table, Binary Search +1
1583	Count Unhappy Friends	Array, Simulation
1599	Maximum Profit of Operating a Centennial Wheel	Array, Simulation
1680	Concatenation of Consecutive Binary Numbers	Bit Manipulation, Math, Simulation
1701	Average Waiting Time	Array, Simulation
1706	Where Will the Ball Fall	Array, Matrix, Simulation
1801	Number of Orders in the Backlog	Array, Simulation, Heap (Priority Queue)
1806	Minimum Number of Operations to Reinitialize a Permutation	Array, Math, Simulation
1823	Find the Winner of the Circular Game	Recursion, Queue, Array +2
1860	Incremental Memory Leak	Math, Simulation
1894	Find the Student that Will Replace the Chalk	Array, Binary Search, Prefix Sum +1
1910	Remove All Occurrences of a Substring	Stack, String, Simulation
1914	Cyclically Rotating a Grid	Array, Matrix, Simulation
2028	Find Missing Observations	Array, Math, Simulation
2043	Simple Bank System	Design, Array, Hash Table +1
2075	Decode the Slanted Ciphertext	String, Simulation
2079	Watering Plants	Array, Simulation
2105	Watering Plants II	Array, Two Pointers, Simulation
2109	Adding Spaces to a String	Array, Two Pointers, String +1
2120	Execution of All Suffix Instructions Staying in a Grid	String, Simulation
2149	Rearrange Array Elements by Sign	Array, Two Pointers, Simulation
2161	Partition Array According to Given Pivot	Array, Two Pointers, Simulation
2177	Find Three Consecutive Integers That Sum to a Given Number	Math, Simulation
2181	Merge Nodes in Between Zeros	Linked List, Simulation
2201	Count Artifacts That Can Be Extracted	Array, Hash Table, Simulation
2211	Count Collisions on a Road	Stack, String, Simulation
2221	Find Triangular Sum of an Array	Array, Math, Combinatorics +1
2257	Count Unguarded Cells in the Grid	Array, Matrix, Simulation
2295	Replace Elements in an Array	Array, Hash Table, Simulation
2326	Spiral Matrix IV	Array, Linked List, Matrix +1
2327	Number of People Aware of a Secret	Queue, Dynamic Programming, Simulation
2352	Equal Row and Column Pairs	Array, Hash Table, Matrix +1
2365	Task Scheduler II	Array, Hash Table, Simulation
2380	Time Needed to Rearrange a Binary String	String, Dynamic Programming, Simulation
2390	Removing Stars From a String	Stack, String, Simulation
2462	Total Cost to Hire K Workers	Array, Two Pointers, Simulation +1
2482	Difference Between Ones and Zeros in Row and Column	Array, Matrix, Simulation
2502	Design Memory Allocator	Design, Array, Hash Table +1
2507	Smallest Value After Replacing With Sum of Prime Factors	Math, Number Theory, Simulation
2593	Find Score of an Array After Marking All Elements	Array, Hash Table, Sorting +2
2596	Check Knight Tour Configuration	Depth-First Search, Breadth-First Search, Array +2
2679	Sum in a Matrix	Array, Matrix, Sorting +2
2766	Relocate Marbles	Array, Hash Table, Sorting +1
2961	Double Modular Exponentiation	Array, Math, Simulation
0348	Design Tic-Tac-ToePremium	Design, Array, Hash Table +2
0353	Design Snake GamePremium	Design, Queue, Array +2
0544	Output Contest MatchesPremium	Recursion, String, Simulation
0723	Candy CrushPremium	Array, Two Pointers, Matrix +1
0755	Pour WaterPremium	Array, Simulation
1756	Design Most Recently Used QueuePremium	Design, Array, Linked List +3
2061	Number of Spaces Cleaning Robot CleanedPremium	Array, Matrix, Simulation
2069	Walking Robot Simulation II	Design, Simulation

Hard (10)

Hard problems
No.	Problem	Topics
0068	Text Justification	Array, String, Simulation
0749	Contain Virus	Depth-First Search, Breadth-First Search, Array +2
1606	Find Servers That Handled Most Number of Requests	Array, Ordered Set, Simulation +1
2056	Number of Valid Move Combinations On Chessboard	Array, String, Backtracking +1
2296	Design a Text Editor	Stack, Design, Linked List +3
2402	Meeting Rooms III	Array, Hash Table, Sorting +2
2532	Time to Cross a Bridge	Array, Simulation, Heap (Priority Queue)
2751	Robot Collisions	Stack, Array, Sorting +1
0158	Read N Characters Given read4 II - Call Multiple TimesPremium	Array, Interactive, Simulation
2534	Time Taken to Cross the DoorPremium	Queue, Array, Simulation

Eyes only

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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+

Simulation problems by difficulty

Easy (57)57

Medium (77)77

Hard (10)10

When the Simulation problem arrives live.

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Easy (57)

Medium (77)

Hard (10)