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# Find the Difference

## [Find the Difference](https://leetcode.com/problems/find-the-difference)

You are given two strings `s` and `t`.

String `t` is generated by random shuffling string `s` and then add one more letter at a random position.

Return the letter that was added to `t`.

**Example 1:**

```

Input: s = "abcd", t = "abcde"
Output: "e"
Explanation: 'e' is the letter that was added.
```

**Example 2:**

```

Input: s = "", t = "y"
Output: "y"
```

**Example 3:**

```

Input: s = "a", t = "aa"
Output: "a"
```

**Example 4:**

```

Input: s = "ae", t = "aea"
Output: "a"
```

**Constraints:**

* `0 <= s.length <= 1000`
* `t.length == s.length + 1`
* `s` and `t` consist of lower-case English letters.

## Solutions

### 🧠 Cpp

```cpp
#define all(x) (x).begin(), (x).end()
class Solution
{

public:
    char findTheDifference(string s, string t)
    {
        std::sort(all(s));
        std::sort(all(t));

        string diff;
        std::set_difference(all(t),
                            all(s),
                            back_inserter(diff));

        return diff.front();
    }
};
```