1963. Minimum Number of Swaps to Make the String Balanced

class Solution {
    public int minSwaps(String s) {
        int size = 0;
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            if (ch == '[') 
                size++;
            else if (size > 0) 
                size--;
        }
        return (size + 1) / 2;
    }
}