OC_链表实现队列

1. @interface Node : NSObject
2. @property(nonatomic,strong)NSString *value;
3. @property(nonatomic,strong)Node *next;

Queue的头文件内容：

1. #import <Foundation/Foundation.h>
2. @class Node;
3. @interface Queue : NSObject
4. @property  (strong,nonatomic) Node  *first;
5. @property  (strong,nonatomic)  Node  *last;
6. @property  (assign,nonatomic) NSInteger  count;
7. -(BOOL)isEmpty;
8. -(NSInteger)size;
9. -(void)enqueue:(NSString *)value;
10. -(NSString *)dequeue;
11. -(void)remove:(NSString *)value;
12. @end
13. Queue的实现内容：
14. #import "Queue.h"
15. #import "Node.h"
16. @implementation Queue
17. -(BOOL)isEmpty{
18.     return self.count==0;
19. }
20. -(NSInteger)size{
21.     return self.count;
22. }
23. -(void)enqueue:(NSString *)value{
24.     Node  *oldLast=self.last;
25.     self.last=[[Node alloc]init];
26.     self.last.data=value;
27.     self.last.next=NULL;
28.     oldLast.next=self.last;
29.     if ([self isEmpty]) {
30.         self.first=self.last;
31.     }else{
32.         oldLast.next=self.last;
33.     }
34.     self.count=self.count+1;
35. }
36. -(NSString *)dequeue{
37.     if ([self isEmpty]) {
38.         return [NSString stringWithFormat:@"-1"];
39.     }
40.     NSString  *result=self.first.data;
41.     self.first=self.first.next;
42.     self.count=self.count-1;
43.     return result;
44. }
45. -(void)remove:(NSString *)value{
46.     //判断是不是头部节点
47.     if ([self.first.data isEqualToString:value]) {
48.         self.first=self.first.next;
49.         self.count=self.count-1;
50.     }else
51.     {
52.         Node  *node=self.first;
53.         while (node!=NULL)
54.         {
55.             if ([node.next.data isEqualToString:value])
56.             {
57.                 node.next=node.next.next;
58.                 self.count=self.count-1;
59.                 break;
60.             }
61.             node=node.next;
62.         }
63.     }
64. }
65. @end