mirror of
https://github.com/TheAlgorithms/Java.git
synced 2025-07-05 16:27:33 +08:00
fixing problem with folder
This commit is contained in:
@ -1,68 +0,0 @@
|
|||||||
/*
|
|
||||||
* A priority queue adds elements into positions based on their priority.
|
|
||||||
* So the most important elements are placed at the front/on the top.
|
|
||||||
* In this example I give numbers that are bigger, a higher priority.
|
|
||||||
* Queues in theory have no fixed size but when using an array implementation it does.
|
|
||||||
*/
|
|
||||||
class PriorityQueue{
|
|
||||||
private int maxSize;
|
|
||||||
private int[] queueArray;
|
|
||||||
private int nItems;
|
|
||||||
|
|
||||||
public PriorityQueue(int size){ //Constructor
|
|
||||||
maxSize = size;
|
|
||||||
queueArray = new int[size];
|
|
||||||
nItems = 0;
|
|
||||||
}
|
|
||||||
|
|
||||||
public void insert(int value){ //Inserts an element in it's appropriate place
|
|
||||||
if(nItems == 0){
|
|
||||||
queueArray[0] = value;
|
|
||||||
}
|
|
||||||
else{
|
|
||||||
int j = nItems;
|
|
||||||
while(j > 0 && queueArray[j-1] > value){
|
|
||||||
queueArray[j] = queueArray[j-1];
|
|
||||||
j--;
|
|
||||||
}
|
|
||||||
queueArray[j] = value;
|
|
||||||
}
|
|
||||||
nItems++;
|
|
||||||
}
|
|
||||||
|
|
||||||
public int remove(){ //Remove the element from the front of the queue
|
|
||||||
return queueArray[--nItems];
|
|
||||||
}
|
|
||||||
|
|
||||||
public int peek(){ //Checks what's at the front of the queue
|
|
||||||
return queueArray[nItems-1];
|
|
||||||
}
|
|
||||||
|
|
||||||
public boolean isEmpty(){ //Returns true is the queue is empty
|
|
||||||
return(nItems == 0);
|
|
||||||
}
|
|
||||||
|
|
||||||
public boolean isFull(){ //Returns true is the queue is full
|
|
||||||
return(nItems == maxSize);
|
|
||||||
}
|
|
||||||
|
|
||||||
public int getSize(){ //Returns the number of elements in the queue
|
|
||||||
return nItems;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
//Example
|
|
||||||
public class PriorityQueues{
|
|
||||||
public static void main(String args[]){
|
|
||||||
PriorityQueue myQueue = new PriorityQueue(4);
|
|
||||||
myQueue.insert(10);
|
|
||||||
myQueue.insert(2);
|
|
||||||
myQueue.insert(5);
|
|
||||||
myQueue.insert(3);
|
|
||||||
//[2, 3, 5, 10] Here higher numbers have higher priority, so they are on the top
|
|
||||||
|
|
||||||
for(int i = 3; i>=0; i--)
|
|
||||||
System.out.print(myQueue.remove() + " "); //will print the queue in reverse order [10, 5, 3, 2]
|
|
||||||
|
|
||||||
//As you can see, a Priority Queue can be used as a sorting algotithm
|
|
||||||
}
|
|
||||||
}
|
|
@ -1,86 +0,0 @@
|
|||||||
/*
|
|
||||||
* A queue data structure functions the same as a real world queue.
|
|
||||||
* The elements that are added first are the first to be removed.
|
|
||||||
* New elements are added to the back/rear of the queue.
|
|
||||||
*/
|
|
||||||
class Queue{
|
|
||||||
private int maxSize;
|
|
||||||
private int[] queueArray;
|
|
||||||
private int front;
|
|
||||||
private int rear;
|
|
||||||
private int nItems;
|
|
||||||
|
|
||||||
public Queue(int size){ //Constructor
|
|
||||||
maxSize = size;
|
|
||||||
queueArray = new int[size];
|
|
||||||
front = 0;
|
|
||||||
rear = -1;
|
|
||||||
nItems = 0;
|
|
||||||
}
|
|
||||||
|
|
||||||
public boolean insert(int x){ //Inserts an element at the rear of the queue
|
|
||||||
if(isFull())
|
|
||||||
return false;
|
|
||||||
if(rear == maxSize-1) //If the back of the queue is the end of the array wrap around to the front
|
|
||||||
rear = -1;
|
|
||||||
rear++;
|
|
||||||
queueArray[rear] = x;
|
|
||||||
nItems++;
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
|
|
||||||
public int remove(){ //Remove an element from the front of the queue
|
|
||||||
if(isEmpty()){
|
|
||||||
System.out.println("Queue is empty");
|
|
||||||
return -1;
|
|
||||||
}
|
|
||||||
int temp = queueArray[front];
|
|
||||||
front++;
|
|
||||||
if(front == maxSize) //Dealing with wrap-around again
|
|
||||||
front = 0;
|
|
||||||
nItems--;
|
|
||||||
return temp;
|
|
||||||
}
|
|
||||||
|
|
||||||
public int peekFront(){ //Checks what's at the front of the queue
|
|
||||||
return queueArray[front];
|
|
||||||
}
|
|
||||||
|
|
||||||
public int peekRear(){ //Checks what's at the rear of the queue
|
|
||||||
return queueArray[rear];
|
|
||||||
}
|
|
||||||
|
|
||||||
public boolean isEmpty(){ //Returns true is the queue is empty
|
|
||||||
return(nItems == 0);
|
|
||||||
}
|
|
||||||
|
|
||||||
public boolean isFull(){ //Returns true is the queue is full
|
|
||||||
return(nItems == maxSize);
|
|
||||||
}
|
|
||||||
|
|
||||||
public int getSize(){ //Returns the number of elements in the queue
|
|
||||||
return nItems;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
//Example
|
|
||||||
public class Queues{
|
|
||||||
public static void main(String args[]){
|
|
||||||
Queue myQueue = new Queue(4);
|
|
||||||
myQueue.insert(10);
|
|
||||||
myQueue.insert(2);
|
|
||||||
myQueue.insert(5);
|
|
||||||
myQueue.insert(3);
|
|
||||||
//[10(front), 2, 5, 3(rear)]
|
|
||||||
|
|
||||||
System.out.println(myQueue.isFull()); //Will print true
|
|
||||||
|
|
||||||
myQueue.remove(); //Will make 2 the new front, making 10 no longer part of the queue
|
|
||||||
//[10, 2(front), 5, 3(rear)]
|
|
||||||
|
|
||||||
myQueue.insert(7); //Insert 7 at the rear which will be index 0 because of wrap around
|
|
||||||
// [7(rear), 2(front), 5, 3]
|
|
||||||
|
|
||||||
System.out.println(myQueue.peekFront()); //Will print 2
|
|
||||||
System.out.println(myQueue.peekRear()); //Will print 7
|
|
||||||
}
|
|
||||||
}
|
|
Reference in New Issue
Block a user