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Copy pathQueue_intArr.java
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66 lines (59 loc) · 994 Bytes
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// Use int array to implement Queue
/**
* Created by xiaoyaoworm on 4/16/16.
*/
public class Queue{
int maxSize;
int[] arr;
int head;
int tail;
int nItems;
public Queue(int size){
maxSize = size;
arr = new int[size];
head = 0;
tail = -1;
nItems = 0;
}
public void enqueue(int num){
if(tail == arr.length-1){
tail = -1;
}
if(nItems == maxSize){
System.out.println("Queue is full, cannot enqueue.");
}
else {
tail++；
arr[tail] = num;
nItems++;
}
}
public int dequeue(){
if(head == -1){
head = arr.length-1;
}
if(nItems == 0){
System.out.println("Queue is empty, cannot dequeue.");
return -1;
} else {
int res= arr[head];
head--;
return res;
}
}
public int peek(){
if(head == -1){
head = arr.length-1;
}
if(nItems == 0){
System.out.println("Queue is empty, cannot peek.");
return -1;
} else {
int res= arr[head];
return res;
}
}
public boolean isEmpty(){
return nItems == 0;
}
}