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Leetcode 2390: Removing Stars From a String

Here, we will learn about how to solve removing Stars From a String problem of leet code 2390 with code and algorithm.

You are given a string str which contains stars * and characters.

In one operation, you can:

  • Choose a star in str.
  • Remove the closest non-star character to its left, as well as remove the star itself.

Return the string after all stars have been removed.

Example:

Input: str = "techie**ind*r"
Output: "techinr"

Input: str = "erase*****"
Output: ""

Input: str = "abb*cdfg*****x*"
Output: "a"

Input: str = "aaaa****a"
Output: "a"

Explanation:

If you look at closely, for each star we remove one closest character towards left side of star.

Algorithm 1:

  • Iterate over string from left to right
    • Take one tmp variable of string type
    • If you find “*” during iteration, then remove the one character from back in tmp string variable
    • If you find any “character” during iteration then add this to tmp string variable
  • return tmp variable string

Removing Stars From a String code in C++

Code 1:

#include <iostream>
#include <algorithm>

using namespace std;

string removeStars(string s) {
        string tmp = "";
        
        // Iterate over input string
        for(auto &ch : s) {
            if(ch == '*') {
                
                // Remove character from back
                tmp.pop_back();
            } else {
                
                // add character to back
                tmp.push_back(ch);
            }
        }
        return tmp;
    }
    
int main()
{
    cout<<removeStars("abb*cdfg*****x*");

    return 0;
}

Output:

a

Code 2:

#include <iostream>
#include <algorithm>

using namespace std;

string removeStars(string s) {
        string tmp = "";
        int count = 0;
        
        int size = s.length() - 1;
        
        while(size >= 0) {
            if(s[size] == '*') {
                count++;
            } else {
                if(count == 0) {
                    tmp += s[size];
                } else {
                    count--;
                }
            }
            size--;
        }
        reverse(tmp.begin(), tmp.end());
        return tmp;
    }
int main()
{
    cout<<removeStars("abb*cdfg***x*");

    return 0;
}

Output:

abc

To check more leetcode problem’s solution. Pls click given below link:

https://www.techieindoor.com/category/leetcode/

Posted in C++, Leetcode, Medium

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