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7. Valid Anagram

easyAsked at Postman

Return true if two strings are anagrams 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. An anagram uses exactly the same characters with the same multiplicities.

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 both

Sort both strings and compare character by character.

Time
O(n log n)
Space
O(n)
return [...s].sort().join('') === [...t].sort().join('');

Tradeoff:

2. Frequency counter

Maintain a 26-slot count; increment on s, decrement on t; check all zero at end.

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

Tradeoff:

Postman-specific tips

Postman expects you to call out the early-length check first, the same way request-body validators bail before parsing when content-length mismatches.

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Output

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