Hash Function LeetCode Problems: 25 Python Solutions

Hash Function problems by difficulty

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

Easy (3)

Easy problems
No.	Problem	Topics
0572	Subtree of Another Tree	Tree, Depth-First Search, Binary Tree +2
0705	Design HashSet	Design, Array, Hash Table +2
0706	Design HashMap	Design, Array, Hash Table +2

Medium (10)

Medium problems
No.	Problem	Topics
0187	Repeated DNA Sequences	Bit Manipulation, Hash Table, String +3
0535	Encode and Decode TinyURL	Design, Hash Table, String +1
0718	Maximum Length of Repeated Subarray	Array, Binary Search, Dynamic Programming +3
1461	Check If a String Contains All Binary Codes of Size K	Bit Manipulation, Hash Table, String +2
2261	K Divisible Elements Subarrays	Trie, Array, Hash Table +3
0694	Number of Distinct IslandsPremium	Depth-First Search, Breadth-First Search, Union Find +2
1062	Longest Repeating SubstringPremium	String, Binary Search, Dynamic Programming +3
1554	Strings Differ by One CharacterPremium	Hash Table, String, Hash Function +1
1698	Number of Distinct Substrings in a StringPremium	Trie, String, Suffix Array +2
2168	Unique Substrings With Equal Digit FrequencyPremium	Hash Table, String, Counting +2

Hard (12)

Hard problems
No.	Problem	Topics
0214	Shortest Palindrome	String, String Matching, Hash Function +1
1044	Longest Duplicate Substring	String, Binary Search, Suffix Array +3
1147	Longest Chunked Palindrome Decomposition	Greedy, Two Pointers, String +3
1316	Distinct Echo Substrings	Trie, String, Hash Function +1
1392	Longest Happy Prefix	String, String Matching, Hash Function +1
1923	Longest Common Subpath	Array, Binary Search, Suffix Array +2
1948	Delete Duplicate Folders in System	Trie, Array, Hash Table +2
1960	Maximum Product of the Length of Two Palindromic Substrings	String, Hash Function, Rolling Hash
2156	Find Substring With Given Hash Value	String, Sliding Window, Hash Function +1
2430	Maximum Deletions on a String	String, Dynamic Programming, String Matching +2
0711	Number of Distinct Islands IIPremium	Depth-First Search, Breadth-First Search, Union Find +2
2223	Sum of Scores of Built Strings	String, Binary Search, String Matching +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.

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...

GPT-6.1 TerraClear chat

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

Hash Function LeetCode Problems: All 25,
With Python Solutions

Hash Function problems by difficulty

Easy (3)

Medium (10)

Hard (12)

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Hash Function problems by difficulty

Easy (3)3

Medium (10)10

Hard (12)12

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Easy (3)

Medium (10)

Hard (12)