CS61B_examprep06 

public class AltList<X, Y> {

    private X item;
    private AltList<Y, X> next;
   
    AltList(X item, AltList<Y, X> next) {
       this.item = item;
       this.next = next;
    }


   public static void main(String[] args) {
      
   AltList<Integer, String> list =
   new AltList<Integer, String>(5,
   new AltList<String, Integer>("cat",
   new AltList<Integer, String>(10,
   new AltList<String, Integer>("dog", null))));
   list.pairsSwapped();
    }
}

 

 

 

解答：

 1 public class AltList<X, Y> {
 2 
 3     private X item;
 4     private AltList<Y, X> next;
 5    
 6     AltList(X item, AltList<Y, X> next) {
 7        this.item = item;
 8        this.next = next;
 9     }
10     public AltList<Y, X> pairsSwapped() { //even and nonzero 
11       AltList<Y, X> list = new AltList<Y, X>(next.item, new AltList<X, Y>(this.item, null));
12       if (next.next != null) {
13          list.next.next = next.next.pairsSwapped();
14       }
15       return list;
16     }
17 
18    public static void main(String[] args) {
19       
20    AltList<Integer, String> list =
21    new AltList<Integer, String>(5,
22    new AltList<String, Integer>("cat",
23    new AltList<Integer, String>(10,
24    new AltList<String, Integer>("dog", null))));
25    list.pairsSwapped();
26     }
27 }

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posted @ 2023-05-19 15:09  哎呦_不想学习哟~  阅读(17)  评论(0)    收藏  举报