Skip to content

solution6.md

Latest commit

 

History

History
42 lines (32 loc) · 1.15 KB

solution6.md

File metadata and controls

42 lines (32 loc) · 1.15 KB

Solution 6: Distributed Anagram Search (Find All Anagrams in a String)

Approach Explanation

We use a sliding window of size len(p) and compare character counts. We can optimize by tracking the number of "matches" (character counts that are exactly equal).

Step-by-Step Logic

  1. If len(p) > len(s), return [].
  2. Count frequencies of p and the first len(p) chars of s.
  3. Slide the window:
    • If window's Counter equals p's Counter, add start index to result.
    • Update Counter by adding one character from right and removing one from left.

Complexity

  • Time Complexity: O(N).
  • Space Complexity: O(1) (26 characters).

Code

from collections import Counter

def find_anagrams(s, p):
    res = []
    ns, np = len(s), len(p)
    if np > ns: return res
    
    pCount = Counter(p)
    sCount = Counter(s[:np])
    
    if pCount == sCount:
        res.append(0)
        
    for i in range(1, ns - np + 1):
        sCount[s[i-1]] -= 1
        if sCount[s[i-1]] == 0:
            del sCount[s[i-1]]
        sCount[s[i+np-1]] += 1
        
        if pCount == sCount:
            res.append(i)
            
    return res