Brackets.java

import java.util.List;
import java.util.ArrayList;

class Solution {
    public int solution(String S) {
        if (S == null || S.length() == 0) return 1;
        if (S.length() % 2 != 0) return 0;
        
        char first = S.charAt(0);
        if (first != '{' && first != '[' && first != '(') return 0;
        
        List<Character> brackets = new ArrayList<>();
        for (char c : S.toCharArray()) {
            if (c == '{' || c == '[' || c == '(') {
                brackets.add(c);
            } else {
                int last = brackets.size() - 1;
                if (last == -1) return 0;

                int diff = c - brackets.get(last);
                if (diff == 1 || diff == 2) {
                     brackets.remove(last);    
                }else {
                    return 0;
                }
            }
        }
        return brackets.size() == 0 ? 1 : 0;
    }
}