> For the complete documentation index, see [llms.txt](https://gl01.gitbook.io/gfg-editorials/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl01.gitbook.io/gfg-editorials/2024/03-2024-march-9/10-remove-all-duplicates-from-a-given-string.md).

# 10. Remove all duplicates from a given string

The problem can be found at the following link: [Question Link](https://www.geeksforgeeks.org/problems/remove-all-duplicates-from-a-given-string4321/1)

## My Approach.

Simple straightforward questions.

* I use an unordered\_set to keep track of characters encountered.
* Iterate through the input string.
* If the current character is not in the set, add it to the output string and insert it into the set.
* Return the output string.

## Time and Auxiliary Space Complexity

* **Time Complexity** : `O(N)`, where N is the length of the input string. We iterate through the string once.
* **Auxiliary Space Complexity** : `O(N)`, where N is the length of the input string.

## Code (C++)

```cpp
class Solution {
public:
    string removeDuplicates(string str) {
        unordered_set<char> st;
        string out;
        for(auto i : str){
            if(st.find(i) == st.end()){
                out += i;
                st.insert(i);
            }
        }
        return out;
    }
};
```

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