Parenthesis Checker

Problem Statement

Pattern:

---

Solution

static boolean ispar(String str) {
	// add your code here
	Deque<Character> stack = new LinkedList<>();
	for (char ch : str.toCharArray()) {
		if (ch == '{' || ch == '(' || ch == '[') stack.push(ch);
		else {
			if (stack.isEmpty()) return false;
			char pop = stack.pop();
			if (ch == '}' && pop != '{') return false;
			if (ch == ')' && pop != '(') return false;
			if (ch == ']' && pop != '[') return false;
		}
	}
	return stack.isEmpty();
}

TC : $O(n)$ SC : $O(n)$

Notes