DDSA Solutions

3223. Minimum Length of String After Operations

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StringHash TableCounting
Time: O(n)
Space: O(26)

Problem Overview

Minimum string length after removing specific patterns AB and CD repeatedly.

Intuition

Minimum string length after removing specific patterns AB and CD repeatedly. Stack simulation.

Algorithm

  1. 1Stack. For each char: if stack.top and (top+char) in {AB, CD}: pop. Else push.

Common Pitfalls

  • •Stack handles nested and chained removals. Same as LC 2696 but with different patterns.
3223.cs
C#
// Approach: For each char if frequency ≥ 3 we can reduce; count final length from frequency parities.
// Time: O(n) Space: O(26)

public class Solution
{
    public int MinimumLength(string s)
    {
        int ans = 0;
        int[] count = new int[26];

        foreach (char c in s)
        {
            count[c - 'a']++;
        }

        for (int i = 0; i < 26; i++)
        {
            if (count[i] > 0)
                ans += count[i] % 2 == 0 ? 2 : 1;
        }

        return ans;
    }
}
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