EasyLeetCode #242Arrays & Hashing

Valid Anagram

Given two strings s and t, return true if t is an anagram of s, and false otherwise. An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase.

Constraints

1 <= s.length, t.length <= 5 * 10^4, s and t consist of lowercase English letters

Examples

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

Output: true

Input: s = "rat", t = "car"

Output: false

Solution Approach

Use HashMap to store element frequencies or mappings. Iterate through array once to build map, then solve based on stored data. Common for two-sum and anagram problems.

Implementation

def twoSum(nums, target):
    num_map = {}
    for i, num in enumerate(nums):
        complement = target - num
        if complement in num_map:
            return [num_map[complement], i]
        num_map[num] = i
    return []

Complexity Analysis

Time Complexity

O(n)

Space Complexity

O(n)

Key Learning Points

HashMap for O(1) lookupsSingle pass solutionComplement/pairing pattern