LeetCode 2390: Removing Stars From a String Solution

Master LeetCode problem 2390 (Removing Stars From a String), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

2390. Removing Stars From a String

Medium

String Stack Simulation

Problem Explanation

Explanation

To solve this problem, we can iterate through the string from left to right. Whenever we encounter a star, we remove the closest non-star character to its left and the star itself. We repeat this process until there are no more stars left in the string.

We can use a stack to keep track of non-star characters encountered so far.
When we encounter a star, we pop the top element from the stack because it is the closest non-star character to the left of the star.
After iterating through the whole string, we reconstruct the final string using the elements left in the stack.

Time Complexity

The time complexity of this solution is O(n), where n is the length of the input string.

Space Complexity

The space complexity of this solution is also O(n) due to the stack used.

Solution Code

public String removeStars(String s) {
    Stack<Character> stack = new Stack<>();
    
    for (char c : s.toCharArray()) {
        if (c == '*') {
            stack.pop();
        } else {
            stack.push(c);
        }
    }
    
    StringBuilder sb = new StringBuilder();
    while (!stack.isEmpty()) {
        sb.insert(0, stack.pop());
    }
    
    return sb.toString();
}

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Frequently Asked Questions

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What is the time complexity of LeetCode 2390 (Removing Stars From a String)?

The time complexity for LeetCode 2390 (Removing Stars From a String) varies by solution. Check the detailed explanation section for specific complexities in Java, C++, and Python implementations.

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