Rec00:23:52Technical interview · 45 min

{}PYsolution.pyREADME.mdRunShared editor · Python 3

# Write your code here

def length_of_longest_substring(s: str) -> int:

last_seen = {}

left = best = 0

for right, ch in enumerate(s):

if ch in last_seen and last_seen[ch] >= left:

left = last_seen[ch] + 1

Test casesConsoleRun your code to see the output.

Case 1Case 2Case 3

Inputs = "abcabcbb"

Expected3

Problem

Longest substring without repeats

Medium

Given a string s, return the length of the longest contiguous substring in which every character is unique.

Example

in s = "abcabcbb"

out 3 ("abc")

Constraints

0 ≤ len(s) ≤ 50,000
s may contain letters, digits, symbols and spaces.

Hint 1Hint 2Topics

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Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

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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Rec00:23:52Technical interview · 45 min

{}PYsolution.pyREADME.mdRunShared editor · Python 3

# Write your code here

def length_of_longest_substring(s: str) -> int:

last_seen = {}

left = best = 0

for right, ch in enumerate(s):

if ch in last_seen and last_seen[ch] >= left:

left = last_seen[ch] + 1

Test casesConsoleRun your code to see the output.

Case 1Case 2Case 3

Inputs = "abcabcbb"

Expected3

Problem

Longest substring without repeats

Medium

Given a string s, return the length of the longest contiguous substring in which every character is unique.

Example

in s = "abcabcbb"

out 3 ("abc")

Constraints

0 ≤ len(s) ≤ 50,000
s may contain letters, digits, symbols and spaces.

Hint 1Hint 2Topics

Auto-saved

DWARConnected · 2 participantsLn 1, Col 1Spaces: 4UTF-8Python 3

You are sharing your screenStop sharing

Dana Whitfield· Interviewer

You

Participants2Chat

DWDana WhitfieldInterviewer

ARYouSharing screen

RecThis meeting is being recorded.

Message everyone

MuteStop videoShare2ParticipantsChatReactionsLeave

90%Subscription

python

Please analyze this context and help me answer the question or solve the problem.

Transcript

"Okay, next one. Given a string, return the length of the longest substring that has no repeating characters. Walk me through your approach before you code it."

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

Transcribing...

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