ValidParentheses.java

class Solution {
    
    static Map<Character, Character> mappings = new HashMap<>();
    static {
        mappings.put('(', ')');
        mappings.put('[', ']');
        mappings.put('{', '}');
    }
    
    public boolean isValid(String s) {        
        Stack<Character> parenthesis = new Stack<>();
    
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
    
            if (mappings.containsKey(c)) {
                parenthesis.push(mappings.get(c));
    
            } else if (mappings.containsValue(c)) {
    
                if (parenthesis.isEmpty() || parenthesis.pop() != c) {
                    return false;
                }
            }
        }
        return parenthesis.isEmpty();
    }
}