10(March) Remove all duplicates from a given string

10. Remove Duplicate Characters

The problem statement can be found at the following link: Question Link

My Approach

1. Initialization:

   • Initialize an empty unordered set seen to store characters that have been encountered.

   • Initialize an empty string result to store the final output.

2. Iteration Process:

   • Iterate through each character c in the input string str.

3. Check for Duplicates:

   • For each character c, check if it has been seen before. If not, append it to the result string and add it to the seen set.

4. Finalization:

   • After iterating through all characters in the input string, return the result string containing unique characters only.

This approach effectively removes duplicate characters from the input string while maintaining the original order of characters.

Time and Auxiliary Space Complexity

• Time Complexity: O(N), where N is the length of the input string.

• Auxiliary Space Complexity: O(N), where N is the length of the input string, for storing unique characters in the unordered set.

Code (C++)

class Solution {
public:
    std::string removeDuplicates(std::string str) {
        std::unordered_set<char> seen;
        std::string result = "";

        for (char& c : str) {
            if (seen.find(c) == seen.end()) {
                result += c;
                seen.insert(c);
            }
        }

        return result;
    }
};

Contribution and Support

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