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Longest Substring

Certification: Advanced Level Accuracy: 0% Submissions: 0 Points: 10

Write a C# program to find the length of the longest substring without repeating characters in a given string. A substring is a contiguous sequence of characters within a string.

Example 1
    
  
  • Input: s = "abcabcbb"
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  • Output: 3
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  • Explanation: 
    
      
      
    • The answer is "abc", with the length of 3.
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    • Step 1: Start with a sliding window at the beginning of the string.
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    • Step 2: Expand the window to the right until we find a repeating character.
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    • Step 3: When a repeating character is found, move the left boundary of the window.
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    • Step 4: "abc" is the longest substring without repeating characters.
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Example 2
    
  
  • Input: s = "bbbbb"
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  • Output: 1
    • 
  
  • Explanation: 
    
      
      
    • The answer is "b", with the length of 1.
      • 
      
    • Step 1: Initialize a sliding window.
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    • Step 2: Since all characters are the same, the maximum length is 1.
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    • Step 3: The longest substring without repeating characters is "b".
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Constraints
    
  
  • 0 ≤ s.length ≤ 5 * 10^4
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  • s consists of English letters, digits, symbols, and spaces.
    • 
  
  • Time Complexity: O(n)
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  • Space Complexity: O(min(n, m)) where m is the size of the character set
    •
StringsAirbnbSwiggy
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Hint
Solution

Solution Hints

    
  
  • Use a sliding window approach to keep track of the current substring
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  • Maintain a hash set or dictionary to check for duplicate characters
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  • When a duplicate is found, shrink the window from the left
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  • Keep track of the maximum length seen so far
    •

Steps to solve by this approach:

 Step 1: Initialize a HashSet to keep track of characters in the current window.
 Step 2: Use two pointers, left and right, to represent the sliding window.
 Step 3: Move the right pointer to expand the window until we find a duplicate character.
 Step 4: When a duplicate is found, move the left pointer and remove characters until the duplicate is removed.
 Step 5: Update the maximum length after each expansion of the window.
 Step 6: Continue this process until we reach the end of the string.
 Step 7: Return the maximum length found.

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