Merge pull request #143 from quanxing/master

添加带头节点翻转和不带头节点翻转以及回文串的实现

java/06_linkedlist/SinglyLinkedList.java

@@ -30,6 +30,9 @@ public class SinglyLinkedList {
         return p;
     }
 
+    //无头结点
+    //表头部插入
+    //这种操作将于输入的顺序相反，逆序
     public void insertToHead(int value) {
         Node newNode = new Node(value, null);
         insertToHead(newNode);
@@ -44,6 +47,24 @@ public class SinglyLinkedList {
         }
     }
 
+    //顺序插入
+    //链表尾部插入
+    public void insertTail(int value){
+
+        Node newNode = new Node(value, null);
+        //空链表，可以插入新节点作为head，也可以不操作
+        if (head == null){
+            head = newNode;
+
+        }else{
+            Node q = head;
+            while(q.next != null){
+                q = q.next;
+            }
+            newNode.next = q.next;
+            q.next = newNode;
+        }
+    }
     public void insertAfter(Node p, int value) {
         Node newNode = new Node(value, null);
         insertAfter(p, newNode);
@@ -146,6 +167,123 @@ public class SinglyLinkedList {
         System.out.println();
     }
 
+    //判断true or false
+    public boolean TFResult(Node left, Node right){
+        Node l = left;
+        Node r = right;
+
+        System.out.println("left_:"+l.data);
+        System.out.println("right_:"+r.data);
+        while(l != null && r != null){
+           if (l.data == r.data){
+               l = l.next;
+               r = r.next;
+               continue;
+           }else{
+               break;
+           }
+
+        }
+
+        System.out.println("什么结果");
+        if (l==null && r==null){
+           System.out.println("什么结果");
+           return true;
+        }else{
+           return false;
+        }
+    }
+    //　判断是否为回文 
+
+    public boolean palindrome(){
+       if (head == null){
+           return false;
+       }else{
+           System.out.println("开始执行找到中间节点");
+           Node p = head;
+           Node q = head;
+           if (p.next == null){
+               System.out.println("只有一个元素");
+               return true;
+           }
+           while( q.next != null && q.next.next != null){
+               p = p.next;
+               q = q.next.next;
+
+           }
+
+           System.out.println("中间节点" + p.data);
+           System.out.println("开始执行奇数节点的回文判断");
+           Node leftLink = null;
+           Node rightLink = null;
+           if(q.next == null){
+               //　p 一定为整个链表的中点，且节点数目为奇数
+               leftLink = inverseLinkList(p);
+               System.out.println("左边第一个节点"+leftLink.data);
+               System.out.println("右边第一个节点"+p.next.data);
+               rightLink = p;
+
+           }else{
+               //p q　均为中点
+               leftLink = inverseLinkList(p);
+               rightLink = q;
+           }
+           return TFResult(leftLink, rightLink);
+
+       }
+    }
+
+    //带结点的链表翻转
+    public Node inverseLinkList_head(Node p){
+        //　Head　为新建的一个头结点
+        Node Head = new Node(9999,null);
+        // p　为原来整个链表的头结点,现在Head指向　整个链表
+        Head.next = p;
+        /*
+        带头结点的链表翻转等价于
+        从第二个元素开始重新头插法建立链表
+        */
+        Node Cur = p.next;
+        p.next = null;
+        Node next = null;
+
+        while(Cur != null){
+            next = Cur.next;
+            Cur.next = Head.next;
+            Head.next = Cur;
+            System.out.println("first " + Head.data);
+
+            Cur = next;
+        }
+
+        //　返回左半部分的中点之前的那个节点
+        //　从此处开始同步像两边比较
+        return Head;
+
+    }
+
+    //无头结点的链表翻转
+    public Node inverseLinkList(Node p){
+
+        Node pre = null;
+        Node r = head;
+        System.out.println("z---" + r.data);
+        Node next= null;
+        while(r !=p){
+            next = r.next;
+
+            r.next = pre;
+            pre = r;
+            r = next;
+        }
+
+        r.next = pre;
+        //　返回左半部分的中点之前的那个节点
+        //　从此处开始同步像两边比较
+        return r;
+
+    }
+    
     public static Node createNode(int value) {
         return new Node(value, null);
     }
@@ -163,5 +301,34 @@ public class SinglyLinkedList {
             return data;
         }
     }
+    public static void main(String[]args){
+
+        SinglyLinkedList link = new SinglyLinkedList(); 
+        System.out.println("hello");
+        //int data[] = {1};
+        //int data[] = {1,2,3,1};
+        int data[] = {1,2,4,5};
+        //int data[] = {1,2,2,1};
+        //int data[] = {1,2,5,2,1};
+
+        for(int i =0; i < data.length; i++){
+            //link.insertToHead(data[i]);
+            link.insertTail(data[i]);
+        }
+        link.printAll();
+        Node p = link.inverseLinkList_head(link.head);
+        while(p != null){
+            System.out.println("aa"+p.data);
+            p = p.next;
+        }
+
+        //System.out.println("打印原始:");
+        //link.printAll();
+        //if (link.palindrome()){
+        //    System.out.println("回文");
+        //}else{
+        //    System.out.println("不是回文");
+        //}
+    }
 
 }