Valid Anagram

Valid Anagram

Question:

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

P.s. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

How to Solve:

First of all, we check whether s and t are even the same length. Then we maintain a hash table (unordered_map in C++) that uses the letters as keys and the frequency of each letter as the corresponding value. We traverse each character of s and increase the corresponding frequencies, then later traverse each character of t and decrease the corresponding frequencies. In the end, we check whether all frequencies are back at zero.

My C++ Solution:

class Solution {
 public:
  bool isAnagram(string s, string t) {
    if (s.length() != t.length()) {
      return false;
    }
    unordered_map<char, int> m;
    for (const auto &ch : s) {
      m[ch] += 1;
    }
    for (const auto &ch : t) {
      m[ch] -= 1;
    }
    for (const auto &pp : m) {
      if (pp.second != 0) {
        return false;
      }
    }
    return true;
  }
};