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# 25- Find the Difference

The problem can be found at the following link: [Question Link](https://leetcode.com/problems/find-the-difference/description)

## My Approach

1. Initialize an unordered\_map called `mp` to store character frequencies.
2. Iterate through each character `c` in string `s`:
   * Increment the count of character `c` in the `mp` map by 1.
   * This loop populates the `mp` map with the frequency of each character in string `s`.
3. Iterate through each character `c` in string `t`:
   * Decrement the count of character `c` in the `mp` map by 1.
   * Check if the count becomes less than 0. If it does, return the character `c`. This character is the one that appears more times in string `t` than in string `s`, making it the "difference" character.
4. If no difference character is found during the loop in step 3, return the null character `'\0'`. This indicates that all characters in `s` and `t` are the same, and there is no additional character in `t`.

## Time and Auxiliary Space Complexity

* Time Complexity: `O(n)`
* Auxiliary Space Complexity: `O(n)`

## Code (C++)

```cpp

class Solution {
public:
    char findTheDifference(string s, string t) {
        unordered_map<char,int> mp;
        for(auto& c:s) mp[c]+=1;
        for(auto& c:t) if(--mp[c]<0) return c;
        return '\0';
    }
};

```

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