Stacks And Queues
Go to ProblemsQueue Implementation Details
C :
Array / Linked list based implementation as shown in earlier lessons.
C++ :
C style array queue works in C++ as well. However, C++ provides a library implementation of queue as well.
Queue declaration : :
queue<int> A; // declares an empty queue.
Push
A.push(newElement); // Pushes a new element. O(1)
Pop
A.pop(); // O(1) pop
isEmpty
A.empty() // O(1)
Size
A.size(); // O(1)
Front
A.front(); // O(1). Gives the first element.
JAVA :
Java has a queue similar to C++.
Queue declaration : :
Queue A = new LinkedList();
Push
A.add(new Integer(newElement)); // Pushes a new element. O(1)
Pop
A.poll(); // O(1) pop
isEmpty
A.isEmpty() // O(1)
Size
A.size(); // O(1)
Front
A.peek(); // O(1). Gives the top element.
PYTHON :
We can use deque as a queue in python.
Queue declaration : :
A = deque() # declares an empty queue. O(1)
Push
A.append(newElement) # Put the new Element on the end of the array. O(1).
Pop
A.popleft() # Pops out the front of the queue
isEmpty
return (len(A) == 0); # Check if size is 0. O(1)
Size
return len(A); # O(1)
Front
A[0] # O(1)
Stacks And Queues Problems
Stack simple
| Problem | Score | Companies | Time | Status |
|---|---|---|---|---|
| Balanced Parantheses! | 200 |
|
15:59 | |
| Simplify Directory Path | 250 |
|
54:00 | |
| Redundant Braces | 300 |
|
42:41 | |
| Min Stack | 400 |
|
43:31 |
Cleverstack
| Problem | Score | Companies | Time | Status |
|---|---|---|---|---|
| MAXSPPROD | 200 |
|
88:22 | |
| Nearest Smaller Element | 350 |
|
41:37 | |
| Largest Rectangle in Histogram | 450 |
|
65:52 |
Bfs
| Problem | Score | Companies | Time | Status |
|---|---|---|---|---|
| Hotel Service | 200 |
|
49:11 |
Queue
| Problem | Score | Companies | Time | Status |
|---|---|---|---|---|
| First non-repeating character in a stream of characters | 200 |
|
58:46 | |
| Sliding Window Maximum | 450 |
|
69:38 |
Stack math
| Problem | Score | Companies | Time | Status |
|---|---|---|---|---|
| Evaluate Expression | 400 |
|
32:46 | |
| Rain Water Trapped | 400 |
|
59:06 |
