Stack and queue in Java
Practice this questionWANT TO UNDERSTAND THE CONCEPT FIRST?Learn Stack and queue in Java
Stack
Use Deque<Integer> stack = new ArrayDeque<>();
Queue
Use Queue<Integer> queue = new LinkedList<>();
Problems to practice
- Valid Parentheses
- Min Stack
- Daily Temperatures
- Largest Rectangle in Histogram
- Sliding Window Maximum
- Implement Queue using Stacks
Example: stack-based validation
Deque<Character> stack = new ArrayDeque<>();
for (char ch : s.toCharArray()) {
if (ch == '(' || ch == '{' || ch == '[') {
stack.push(ch);
} else if (!stack.isEmpty() && isMatching(stack.peek(), ch)) {
stack.pop();
} else {
return false;
}
}
return stack.isEmpty();Adapted from 15_DSA_JAVA.md · “5. Stack and queue in Java”. Code examples are study fragments. Difficulty and core labels are editorial estimates; version-specific behavior should be checked against your project.