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Find All Anagrams in a String

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

Write a C# program to find all the start indices of anagrams of a given pattern string in a text string. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, using all the original letters exactly once.

Example 1
    
  
  • Input: s = "cbaebabacd", p = "abc"
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  • Output: [0, 6]
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  • Explanation: 
      
      
    • The substring with start index = 0 is "cba", which is an anagram of "abc".
      • 
      
    • The substring with start index = 6 is "bac", which is an anagram of "abc".
      • 
    
    •
Example 2
    
  
  • Input: s = "abab", p = "ab"
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  • Output: [0, 1, 2]
    • 
  
  • Explanation: 
      
      
    • The substring with start index = 0 is "ab", which is an anagram of "ab".
      • 
      
    • The substring with start index = 1 is "ba", which is an anagram of "ab".
      • 
      
    • The substring with start index = 2 is "ab", which is an anagram of "ab".
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Constraints
    
  
  • 1 <= s.length, p.length <= 3 * 10^4
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  • s and p consist of lowercase English letters
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  • Time Complexity: O(n), where n is the length of string s
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  • Space Complexity: O(1), as we're using fixed-size arrays
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Hint
Solution

Solution Hints

    
  
  • Use the sliding window technique with frequency counting
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  • Maintain a window of size p.Length and slide it through the string s
    • 
  
  • Use arrays or hash maps to store character frequencies
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  • Compare character frequencies to determine if a window contains an anagram
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  • Optimize by updating the frequencies as the window slides
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Steps to solve by this approach:

 Step 1: Create two frequency arrays (or hash maps) for counting characters in p and the current window in s.
 Step 2: Initialize the frequency count for pattern p.
 Step 3: Initialize the first sliding window of size p.length() in s.
 Step 4: Check if the first window is an anagram of p.
 Step 5: Slide the window by adding a new character and removing the oldest character.
 Step 6: After each slide, check if the current window is an anagram of p.
 Step 7: If it is an anagram, add the starting index to the result.

Submitted Code :