Valid Anagram

Hi everyone!
Today I solved a string problem where we need to check whether two strings are anagrams of each other.

Problem
Given two strings s and t, return True if t is an anagram of s, else return False.

An anagram means both strings have the same characters with same frequency, just arranged differently.

Example:
Input: s = "anagram", t = "nagaram"

Output: True

My Approach
At first, I thought of sorting both strings and comparing them.
But that would take O(n log n) time.
Then I used a better approach:

Count character frequencies using an array

Logic

• If lengths are different → return False
• Create a count array of size 26 (for lowercase letters)
• Traverse both strings together:
  • Increase count for s
  • Decrease count for t
• At the end, if all values are 0 → anagram

Code (Python)
class Solution:
def isAnagram(self, s: str, t: str) -> bool:
if len(s) != len(t):
return False

    count = [0] * 26

    for a, b in zip(s, t):
        count[ord(a) - ord('a')] += 1
        count[ord(b) - ord('a')] -= 1

    return all(c == 0 for c in count)

Time & Space Complexity

• Time: O(n)
• Space: O(1) (fixed size array)

Key Insight

Instead of sorting, we can use frequency counting, which is faster and more efficient.

What I Learned

• Frequency arrays are useful for string problems
• Avoid sorting when linear solutions exist
• ord() helps map characters to indices

Thanks for reading!
Feel free to share other approaches like hashmap or sorting.