Stack/ Queue

✅ Stack

input, output same direction
LIFO

💡 usage

• DFS
• 문자열 역순
• 연산자 후위표기법

💡 methods

• push
• pop
• isEmpty
• isFull: requires MAX_SIZE

✅ Queue

input, output different direction
front: deQueue
rear: enQueue
FIFO

💡 usage

• linked list
• buffer
• BFS

⭐️ Can you make a queue with stack?

YES, with two stacks I can make a queue

1. main stack enque 12345

main stack: 12345

1. pop main stack, enqueue in substack

main stack:
sub stack: 54321

1. Deque: pop from substack

main stack:
sub stack: 5432

pop: 1
⭐️ like queue FIFO, first number 1 is popped

1. Enqueue: pop substack, enqueue in mainstack then enqueue new number 6

main stack: 23456
substack:
⭐️ like queue FIFO, 6 is added to the end

⭐️ Can you share stack resource to another stack?

• cannot directly
• but can share data structure that can store stack
  • such as array
• and thus, share resource

⭐️ Homogeneity

• queue and stack are consisted of same data type
• linear data type, keeps order

💡 Reference

https://soheeparklee.github.io/posts/JAVA_stack_queue/