242. Valid Anagram

Return true if t is an anagram of s, i.e. uses exactly the same letters the same number of times.

For lowercase letters, a fixed array of 26 counters does the same job as a map. Increment for s and decrement for t in the same loop.

1function isAnagram(s: string, t: string): boolean {
2  if (s.length !== t.length) return false;
3  const cnt = new Array(26).fill(0);
4  for (let i = 0; i < s.length; i++) {
5    cnt[s.charCodeAt(i) - 97]++;
6    cnt[t.charCodeAt(i) - 97]--;
7  }
8  return cnt.every((c) => c === 0);
9}

i = 0

counts (letters that appear)

-1

+1 'a', −1 'n'.

1 / 0

Space: play/pause · ←/→: step