Bitmask LeetCode Problems: 43 Python Solutions

1 pattern

How Bitmask problems are solved

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

Bit ManipulationUse XOR, masks and the low-bit trick to replace whole data structures with an integer.

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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.

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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...

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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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Bitmask problems by difficulty

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

Medium (16)

Medium problems
No.	Problem	Topics
0464	Can I Win	Bit Manipulation, Memoization, Math +3
0473	Matchsticks to Square	Bit Manipulation, Array, Dynamic Programming +2
0526	Beautiful Arrangement	Bit Manipulation, Array, Dynamic Programming +2
0638	Shopping Offers	Bit Manipulation, Memoization, Array +3
0698	Partition to K Equal Sum Subsets	Bit Manipulation, Memoization, Array +3
1947	Maximum Compatibility Score Sum	Bit Manipulation, Array, Dynamic Programming +2
1986	Minimum Number of Work Sessions to Finish the Tasks	Bit Manipulation, Array, Dynamic Programming +2
2002	Maximum Product of the Length of Two Palindromic Subsequences	Bit Manipulation, String, Dynamic Programming +2
2305	Fair Distribution of Cookies	Bit Manipulation, Array, Dynamic Programming +2
2572	Count the Number of Square-Free Subsets	Bit Manipulation, Array, Math +2
2741	Special Permutations	Bit Manipulation, Array, Dynamic Programming +1
0351	Android Unlock PatternsPremium	Bit Manipulation, Dynamic Programming, Backtracking +1
1066	Campus Bikes IIPremium	Bit Manipulation, Array, Dynamic Programming +2
2152	Minimum Number of Lines to Cover PointsPremium	Bit Manipulation, Geometry, Array +5
2184	Number of Ways to Build Sturdy Brick WallPremium	Bit Manipulation, Array, Dynamic Programming +1
2992	Number of Self-Divisible PermutationsPremium	Bit Manipulation, Array, Math +4

Hard (27)

Hard problems
No.	Problem	Topics
0691	Stickers to Spell Word	Bit Manipulation, Memoization, Array +5
0805	Split Array With Same Average	Bit Manipulation, Array, Math +2
0847	Shortest Path Visiting All Nodes	Bit Manipulation, Breadth-First Search, Graph +2
0943	Find the Shortest Superstring	Bit Manipulation, Array, String +2
0996	Number of Squareful Arrays	Bit Manipulation, Array, Hash Table +4
1125	Smallest Sufficient Team	Bit Manipulation, Array, Dynamic Programming +1
1255	Maximum Score Words Formed by Letters	Bit Manipulation, Array, Hash Table +5
1349	Maximum Students Taking Exam	Bit Manipulation, Array, Dynamic Programming +2
1434	Number of Ways to Wear Different Hats to Each Other	Bit Manipulation, Array, Dynamic Programming +1
1494	Parallel Courses II	Bit Manipulation, Graph, Dynamic Programming +1
1595	Minimum Cost to Connect Two Groups of Points	Bit Manipulation, Array, Dynamic Programming +2
1617	Count Subtrees With Max Distance Between Cities	Bit Manipulation, Tree, Dynamic Programming +2
1655	Distribute Repeating Integers	Bit Manipulation, Array, Dynamic Programming +2
1659	Maximize Grid Happiness	Bit Manipulation, Memoization, Dynamic Programming +1
1681	Minimum Incompatibility	Bit Manipulation, Array, Dynamic Programming +1
1723	Find Minimum Time to Finish All Jobs	Bit Manipulation, Array, Dynamic Programming +2
1755	Closest Subsequence Sum	Bit Manipulation, Array, Two Pointers +3
1799	Maximize Score After N Operations	Bit Manipulation, Array, Math +4
1815	Maximum Number of Groups Getting Fresh Donuts	Bit Manipulation, Memoization, Array +2
1879	Minimum XOR Sum of Two Arrays	Bit Manipulation, Array, Dynamic Programming +1
1994	The Number of Good Subsets	Bit Manipulation, Array, Hash Table +5
2035	Partition Array Into Two Arrays to Minimize Sum Difference	Bit Manipulation, Array, Two Pointers +4
2172	Maximum AND Sum of Array	Bit Manipulation, Array, Dynamic Programming +1
2791	Count Paths That Can Form a Palindrome in a Tree	Bit Manipulation, Tree, Depth-First Search +2
0465	Optimal Account BalancingPremium	Bit Manipulation, Array, Dynamic Programming +2
2247	Maximum Cost of Trip With K HighwaysPremium	Bit Manipulation, Graph, Dynamic Programming +1
2403	Minimum Time to Kill All MonstersPremium	Bit Manipulation, Array, Dynamic Programming +1

Bitmask LeetCode Problems: All 43,
With Python Solutions

How Bitmask problems are solved

When the Bitmask problem arrives live.

Approach

Approach

Approach

Bitmask problems by difficulty

Medium (16)

Hard (27)

Keep exploring

How Bitmask problems are solved

When the Bitmask problem arrives live.

Approach

Approach

Approach

Bitmask problems by difficulty

Medium (16)16

Hard (27)27

Keep exploring

Medium (16)

Hard (27)