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Leetcode 2716. Minimize String Length

Problem Statement

You are given a string s consisting of lowercase English letters. Your task is to minimize the length of the string by performing the following operation any number of times:

Find the minimum possible length of the resulting string after performing the above operation any number of times.

Clarifying Questions

  1. Does the removal of the two adjacent equal letters happen simultaneously in one operation, or is it a sequential process?
  2. What is the maximum possible length of the input string?
  3. Can the input string be empty?

Assuming typical problem constraints:

  1. Removal happens sequentially in each operation.
  2. The length of the string is constrained by typical LeetCode limits (up to (10^5) characters).
  3. The input string can be empty.

Strategy

We can use a stack-based approach to solve this problem. The key insight is that if two adjacent characters in the string are the same, they will cancel each other out. Using a stack, we can efficiently process and remove these adjacent pairs:

  1. Iterate through each character in the string.
  2. For each character, check the top of the stack.
    • If the stack is not empty and the top of the stack is the same as the current character, pop the stack (i.e., remove the top character).
    • Otherwise, push the current character onto the stack.
  3. After processing all characters, the remaining characters in the stack represent the minimized string.

The length of the stack at the end gives the desired minimized string length.

Time Complexity

Here is the solution in C++:

#include <iostream>
#include <string>
#include <stack>

int minimizeStringLength(const std::string& s) {
    std::stack<char> stack;
    
    for (char c : s) {
        if (!stack.empty() && stack.top() == c) {
            stack.pop(); // Remove the pair of adjacent equal characters
        } else {
            stack.push(c); // Push the current character onto the stack
        }
    }
    
    return stack.size();
}

int main() {
    std::string s;
    std::cout << "Enter the string: ";
    std::cin >> s;

    int result = minimizeStringLength(s);
    std::cout << "The minimized string length is: " << result << std::endl;

    return 0;
}

This code includes a main function for testing, where you can enter the string, and it will print out the minimized length. The minimizeStringLength function implements the stack-based approach to solving the problem.

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