1.8 KiB
1.8 KiB
title |
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Create a Circular Queue |
Create a Circular Queue
Method:
- In this challenge we create a Circular Queue data structure.
- First, we need to create an array of
size
with all elements set tonull
. - Then we create an equeue method, which moves the write pointer but doesnt exceed the read pointer.
- The dequeue method on the other hand, moves the read pointer but doesnt exceed the write pointer.
- Example:
- First, we create an array of length 5:
[null, null, null, null, null] ^Read @ 0 ^Write @ 0
- Then we enqueue
a
,b
, andc
:
[a, b, c, null, null] ^Read @ 0 ^Write @ 3
- Now we dequeue all the enqueued items:
[null, null, null, null, null] ^Read @ 3 ^Write @ 3
- Finally, we enqueue
d
,e
andf
:
[f, null, null, d, e] ^Read @ 3 ^Write @ 1
Solution:
class CircularQueue {
constructor(size) {
this.queue = [];
this.read = 0;
this.write = 0;
this.max = size - 1;
while (size > 0) {
this.queue.push(null);
size--;
}
}
print() {
return this.queue;
}
enqueue(item) {
if (this.queue[this.write] === null){
this.queue[this.write++] = item;
if (this.write > this.max) this.write = 0;
return item;
}
return null;
}
dequeue() {
if (this.queue[this.read] != null){
let item = this.queue[this.read];
this.queue[this.read++] = null;
if (this.read > this.max) this.read = 0;
return item;
}
return null;
}
}