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Longest Substring Without Repeating Characters

Certification: Intermediate 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"
    • 
  
  • Output: 3
    • 
  
  • Explanation: The substring "abc" has a length of 3 with no repeating characters.
    There are several substrings without repeating characters: "a", "b", "c", "ab", "bc", "ca", "abc", etc.
    Among these, "abc" is one of the longest with a length of 3.
    Therefore, the output is 3.
    •
Example 2
    
  
  • Input: s = "bbbbb"
    • 
  
  • Output: 1
    • 
  
  • Explanation: The longest substring without repeating characters is "b" with a length of 1.
    All other substrings of length greater than 1 contain repeating characters.
    Therefore, the output is 1.
    •
Constraints
    
  
  • 0 ≤ s.length ≤ 5 * 10^4
    • 
  
  • s consists of English letters, digits, symbols and spaces
    • 
  
  • Time Complexity: O(n), where n is the length of the string
    • 
  
  • Space Complexity: O(min(m,n)), where m is the size of the character set and n is the length of the string
    •
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Hint
Solution

Solution Hints

    
  
  • Use a sliding window approach to track the current substring without repeating characters
    • 
  
  • Maintain a set or hash table to check if a character exists in the current substring
    • 
  
  • Use two pointers to represent the start and end of the current substring
    • 
  
  • When you encounter a repeating character, move the start pointer to the right of the previous occurrence of that character
    • 
  
  • Keep track of the maximum length encountered so far
    •

Steps to solve by this approach:

 Step 1: Initialize variables to track the start of the window, current length, and maximum length.

 Step 2: Create an array or hash table to store the last position of each character.

 Step 3: Iterate through the string character by character.

 Step 4: For each character, check if it has been seen before and is within the current window.

 Step 5: If the character is a repeat in the current window, update the start position to the right of the last occurrence.

 Step 6: Update the position of the current character in the hash table.

 Step 7: Calculate the current window length and update the maximum length if needed.

Submitted Code :