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Copy pathDesignCircularDeque.java
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140 lines (126 loc) · 4.47 KB
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// Design your implementation of the circular double-ended queue (deque).
// Your implementation should support following operations:
// - MyCircularDeque(k): Constructor, set the size of the deque to be k.
// - insertFront(): Adds an item at the front of Deque. Return true if the operation is successful.
// - insertLast(): Adds an item at the rear of Deque. Return true if the operation is successful.
// - deleteFront(): Deletes an item from the front of Deque. Return true if the operation is successful.
// - deleteLast(): Deletes an item from the rear of Deque. Return true if the operation is successful.
// - getFront(): Gets the front item from the Deque. If the deque is empty, return -1.
// - getRear(): Gets the last item from Deque. If the deque is empty, return -1.
// - isEmpty(): Checks whether Deque is empty or not.
// - isFull(): Checks whether Deque is full or not.
// See: https://leetcode.com/problems/design-circular-deque/
package leetcode.design;
public class DesignCircularDeque {
// TODO: Use `mod` operator for concise solution
class MyCircularDeque {
int rear = 0;
int front = -1;
int[] arr;
int len = 0;
/** Initialize your data structure here. Set the size of the deque to be k. */
public MyCircularDeque(int k) {
arr = new int[k];
}
/**
* Adds an item at the front of Deque. Return true if the operation is
* successful.
*/
public boolean insertFront(int value) {
if (!isFull()) {
if (front == -1) {
front = 0;
rear = 0;
} else if (front == 0) {
front = arr.length - 1;
} else --front;
arr[front] = value;
len++;
return true;
}
return false;
}
/**
* Adds an item at the rear of Deque. Return true if the operation is
* successful.
*/
public boolean insertLast(int value) {
if (!isFull()) {
if (front == -1) {
front = 0;
rear = 0;
} else if (rear == arr.length - 1) {
rear = 0;
} else ++rear;
arr[rear] = value;
len++;
return true;
}
return false;
}
/**
* Deletes an item from the front of Deque. Return true if the operation is
* successful.
*/
public boolean deleteFront() {
if (!isEmpty()) {
if (len == 1) {
front = -1;
rear = -1;
} else if (front == arr.length - 1) {
front = 0;
} else ++front;
len--;
return true;
}
return false;
}
/**
* Deletes an item from the rear of Deque. Return true if the operation is
* successful.
*/
public boolean deleteLast() {
if (!isEmpty()) {
if (len == 1) {
front = -1;
rear = -1;
} else if (rear == 0) {
rear = arr.length - 1;
} else --rear;
len--;
return true;
}
return false;
}
/** Get the front item from the deque. */
public int getFront() {
if (isEmpty())
return -1;
return arr[front];
}
/** Get the last item from the deque. */
public int getRear() {
if (isEmpty())
return -1;
return arr[rear];
}
/** Checks whether the circular deque is empty or not. */
public boolean isEmpty() {
return len == 0;
}
/** Checks whether the circular deque is full or not. */
public boolean isFull() {
return len == arr.length;
}
}
public static void main(String[] args) {
MyCircularDeque q = new DesignCircularDeque().new MyCircularDeque(3);
System.out.println(q.insertFront(7));
System.out.println(q.deleteLast());
System.out.println(q.getFront());
System.out.println(q.insertLast(5));
System.out.println(q.insertFront(0));
System.out.println(q.getFront());
System.out.println(q.getRear());
}
}