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Valid Anagram

Difficulty: Easy

Problem Description

Given two strings s and t, return true if t is an anagram of s, and false otherwise.

Key Insights

  • An anagram is a rearrangement of the letters in another word.
  • Two strings must have the same length to be anagrams.
  • The frequency of each character must match in both strings.

Space and Time Complexity

Time Complexity: O(n), where n is the length of the strings. Space Complexity: O(1), since the size of the character set is fixed (lowercase English letters).

Solution

To determine if two strings are anagrams, we can utilize a frequency count of each character. We can use a hash table (or dictionary) to count the occurrences of each character in the first string and then decrement the counts using the characters from the second string. If all counts return to zero, the strings are anagrams.

Code Solutions

def isAnagram(s: str, t: str) -> bool:
    # If lengths are not equal, they cannot be anagrams
    if len(s) != len(t):
        return False
    
    # Create a frequency dictionary for characters in s
    count = {}
    for char in s:
        count[char] = count.get(char, 0) + 1
    
    # Decrease the frequency based on characters in t
    for char in t:
        if char in count:
            count[char] -= 1
            if count[char] < 0:
                return False
        else:
            return False
    
    return True
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