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Update linkedlist_deque.java

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This commit is contained in:
Yudong Jin
2023-01-20 02:56:50 +08:00
parent 43d8520291
commit 31eefe028a
1 changed files with 13 additions and 7 deletions
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20
codes/java/chapter_stack_and_queue/linkedlist_deque.java
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@ -43,7 +43,7 @@ class LinkedListDeque {
private void offer(int num, boolean isFront) {
ListNode node = new ListNode(num);
// 若链表为空，则令 front, rear 都指向 node
if (size() == 0)
if (isEmpty())
front = rear = node;
// 队首入队操作
else if (isFront) {
@ -74,7 +74,7 @@ class LinkedListDeque {
/* 出队操作 */
private Integer poll(boolean isFront) {
// 若队列为空，直接返回 null
if (size() == 0)
if (isEmpty())
return null;
int val;
// 队首出队操作
@ -114,17 +114,17 @@ class LinkedListDeque {
/* 访问队首元素 */
public Integer peekFirst() {
return size() != 0 ? front.val : null;
return isEmpty() ? null : front.val;
}
/* 访问队尾元素 */
public Integer peekLast() {
return size() != 0 ? rear.val : null;
return isEmpty() ? null : rear.val;
}
/* 打印双向队列 */
public void print() {
if (size() == 0) {
if (isEmpty()) {
System.out.println("[ ]");
return;
}
@ -153,9 +153,12 @@ public class linkedlist_deque {
System.out.printf("元素 %d 队尾入队后，队列为\n", num);
deque.print();
}
/* 获取队尾元素 */
int last = deque.peekLast();
System.out.printf("队尾元素为 %d\n", last);
/* 队尾出队 */
while (!deque.isEmpty()) {
int last = deque.pollLast();
last = deque.pollLast();
System.out.printf("队尾出队元素为 %d ，队列为\n", last);
deque.print();
}
@ -166,9 +169,12 @@ public class linkedlist_deque {
System.out.printf("元素 %d 队首入队后，队列为\n", num);
deque.print();
}
/* 获取队尾元素 */
int first = deque.peekFirst();
System.out.printf("队首元素为 %d\n", first);
/* 队首出队 */
while (!deque.isEmpty()) {
int first = deque.pollFirst();
first = deque.pollFirst();
System.out.printf("队首出队元素为 %d ，队列为\n", first);
deque.print();
}