Merge Sort LeetCode Problems: 11 Python Solutions

1 pattern

How Merge Sort problems are solved

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

SortingSpend O(n log n) once to buy an ordering that makes the rest of the problem trivial.

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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...

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...

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

Merge Sort problems by difficulty

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

Medium (3)

Medium problems
No.	Problem	Topics
0148	Sort List	Linked List, Two Pointers, Divide and Conquer +2
0912	Sort an Array	Array, Divide and Conquer, Bucket Sort +5
2031	Count Subarrays With More Ones Than ZerosPremium	Binary Indexed Tree, Segment Tree, Array +5

Hard (8)

Hard problems
No.	Problem	Topics
0023	Merge k Sorted Lists	Linked List, Divide and Conquer, Heap (Priority Queue) +1
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
0493	Reverse Pairs	Binary Indexed Tree, Segment Tree, Array +4
1649	Create Sorted Array through Instructions	Binary Indexed Tree, Segment Tree, Array +4
2179	Count Good Triplets in an Array	Binary Indexed Tree, Segment Tree, Array +4
2426	Number of Pairs Satisfying Inequality	Binary Indexed Tree, Segment Tree, Array +4
2519	Count the Number of K-Big IndicesPremium	Binary Indexed Tree, Segment Tree, Array +4

Merge Sort LeetCode Problems: All 11,
With Python Solutions

How Merge Sort problems are solved

When the Merge Sort problem arrives live.

Approach

Approach

Approach

Merge Sort problems by difficulty

Medium (3)

Hard (8)

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How Merge Sort problems are solved

When the Merge Sort problem arrives live.

Approach

Approach

Approach

Merge Sort problems by difficulty

Medium (3)3

Hard (8)8

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Medium (3)

Hard (8)