// 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++ï¼› 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; } }