notes/OJ notes/pages/Leetcode Valid-Anagram.md

# Leetcode Valid-Anagram

#### 2022-06-14 13:36

---

##### Algorithms:

#algorithm #hash_table

##### Data structures:

#DS #array

##### Difficulty:

#leetcode #coding_problem #difficulty_easy

##### Related topics:

##### Links:

- [Link to problem](https://leetcode.com/problems/valid-anagram/)

---

### Problem

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, typically using all the original letters exactly once.

**Follow up:** What if the inputs contain Unicode characters? How would you adapt your solution to such a case?

#### Examples

**Example 1:**

```markdown
**Input:** s = "anagram", t = "nagaram"
**Output:** true
```

**Example 2:**

```markdown
**Input:** s = "rat", t = "car"
**Output:** false
```

#### Constraints

- `1 <= s.length, t.length <= 5 * 104`
- `s` and `t` consist of lowercase English letters.

### Thoughts

The difference between this and [[Leetcode Ransom-Note]] is that ransom note checks the hash table one way, and this one is bidirectional, which means not only hash map has to be >= 0, it also has to be <= 0, which results in it can only be 0.

> [!tip]- To understand that
> Compare this solution with [[Leetcode Ransom-Note#Solution]]
> to better understand what I mean.

**Follow up question:**
Refer to this [site](https://www.cprogramming.com/tutorial/unicode.html) and this [answer](https://stackoverflow.com/questions/3010739/how-to-use-unicode-in-c/3019339#3019339)

### Solution

```cpp
class Solution {
public:
  bool isAnagram(string s, string t) {
    int hashTable[26] = {};

    for (char c : s) {
      hashTable[c - 'a']++;
    }

    for (char c : t) {
      hashTable[c - 'a']--;
    }

    for (int i : hashTable) {
      if (i != 0) {
        return false;
      }
    }
    return true;
  }
};

```