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242. Valid Anagram

easyAsked at GoDaddy

Check if two strings contain the exact same characters in the same counts — GoDaddy uses this hash-map frequency pattern in their domain-suggestion pipeline to detect whether two brand-name candidates are character-for-character rearrangements of each other.

By Alex Chen, Founder, InterviewChamp.AI · Last verified

Problem

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

Constraints

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

Examples

Example 1

Input
s = "anagram", t = "nagaram"
Output
true

Example 2

Input
s = "rat", t = "car"
Output
false

Approaches

1. Sort and compare

Sort both strings and check equality — simple but O(n log n).

Time
O(n log n)
Space
O(n)
function isAnagram(s, t) {
  if (s.length !== t.length) return false;
  return s.split('').sort().join('') === t.split('').sort().join('');
}

Tradeoff:

2. Character frequency count

Increment a 26-element array for s, decrement for t; any non-zero entry means the strings differ.

Time
O(n)
Space
O(1)
function isAnagram(s, t) {
  if (s.length !== t.length) return false;
  const count = new Array(26).fill(0);
  for (let i = 0; i < s.length; i++) {
    count[s.charCodeAt(i) - 97]++;
    count[t.charCodeAt(i) - 97]--;
  }
  return count.every(c => c === 0);
}

Tradeoff:

GoDaddy-specific tips

GoDaddy uses Valid Anagram as a warm-up to confirm you know O(n) frequency counting, and then immediately extends it to Unicode strings — ask about the follow-up: with Unicode characters you'd use a Map instead of the fixed 26-element array, which shows you understand the constraint boundary.

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Output

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