IT公司100题-1

 1 // 题目：
 2 // 输入一棵二元查找树，将该二元查找树转换成一个排序的双向链表。
 3 // 要求不能创建任何新的结点，只调整指针的指向。
 4
 5 //    10
 6 //    / /
 7 //   6  14
 8 // / / / /
 9 // 4  8 12 16
10
11 // 转换成双向链表
12 // 4=6=8=10=12=14=16。
13
14 #include <iostream>
15 using namespace std;
16
17 class Node{
18   public:
19     int data;
20     Node *left;
21     Node *right;
22
23     Node(int d = 0, Node *lr = 0, Node *rr = 0):data(d), left(lr), right(rr){}
24 };
25
26 Node *create()
27 {
28   Node *root;
29   Node *p4 = new Node(4);
30   Node *p8 = new Node(8);
31   Node *p6 = new Node(6, p4, p8);
32
33   Node *p12 = new Node(12);
34   Node *p16 = new Node(16);
35   Node *p14 = new Node(14, p12, p16);
36
37   Node *p10 = new Node(10, p6, p14);
38   root = p10;
39
40   return root;
41 }
42
43 Node *change(Node *p, bool asRight)
44 {
45   if (!p)
46     return NULL;
47   Node *pLeft = change(p->left, false);
48   if (pLeft)
49     pLeft->right = p;
50   p->left = pLeft;
51
52   Node *pRight = change(p->right, true);
53   if (pRight)
54     pRight->left = p;
55   p->right = pRight;
56
57   Node *r = p;
58   if (asRight)
59   {
60     while (r->left)
61       r = r->left;
62   }else{
63     while (r->right)
64       r = r->right;
65   }
66   return r;
67 }
68
69 int main(){
70   Node *root = create();
71   Node *tail = change(root, false);
72   while (tail)
73   {
74     cout << tail->data << " ";
75     tail = tail->left;
76   }
77   cout << endl;
78
79   root = create();
80   Node *head = change(root, true);
81   while (head)
82   {
83     cout << head->data << " ";
84     head = head->right;
85   }
86   cout << endl;
87   return 1;
88 }