Stack
interfaces:
stack.sizestack.peek()stack.pushstack.pop()stack.isEmpty()stack.clear()
implementation:
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46/*
* Note: this version use `null` as Error symbol,
* so you cannot push null into the stack
*/
class Stack{
constructor(){ this.data = [] }
get size(){ return this.data.length }
isEmpty(){ return this.data.length === 0 }
peek(){ return this.data[this.data.length-1] }
push(item){
if( typeof item ==="undefined" || item === null ) return false
this.data.push(item)
return true
}
pop(item){
if(this.data.length === 0) return null
return this.data.pop();
}
clear(){ this.data = [] }
}
/* ---- Testing ---- */
let s = new Stack()
console.log("size: ",s.size) // 0
console.log(s.pop()) // null
console.log(s.push()) // false
console.log(s.push(null)) // false
console.log(s.push(1)) // true
console.log(s.push(1)) // true
console.log("size: ",s.size) // 2
console.log(s.push(2)) // true
console.log("size: ",s.size) // 3
console.log(s.pop()) // 2
console.log("size: ", s.size) // 2
console.log(s.pop()) // 1
console.log(s.pop()) // 1
console.log("size: ", s.size) // 0
console.log(s.pop()) // null
console.log("size: ", s.size) // 0
console.log(s.isEmpty()) // true
Queue
interfaces:
queue.sizequeue.peek()queue.pushqueue.pop()queue.isEmpty()queue.clear()
implementation:
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39/*
* Note: this version can add any object into Queue
* But need to call `isEmpty()` when necessary
*/
class Queue{
constructor(){ this.items = [] }
get size(){ return this.items.length; }
isEmpty(){ return this.items.length === 0 }
offer(item){ this.items.push(item) }
poll(){ return this.items.shift() }
peek(){ return this.items[0] }
clear(){ this.items = [] }
}
/* ---- Testing ---- */
let q = new Queue()
console.log("size: ", q.size)// 0
console.log(q.offer(null))
console.log(q.offer(null))
console.log(q.items) // [null, null]
console.log(q.offer(1))
console.log(q.items) // [null, null, 1]
console.log(q.poll()) // null
console.log(q.offer(2)) // [null, 1, 2]
console.log("size: ",q.size)// 3
console.log(q.poll())
console.log(q.items) // [1, 2]
console.log(q.poll()) // 1
console.log(q.items) // [2]
console.log("size: ", q.size)// 1
console.log(q.poll()) // 2
console.log("size: ", q.size)// 0
console.log(q.isEmpty()) // true