二叉树重建

根据二叉树的先序遍历和中序遍历重建二叉树。

  1 #include <iostream>
  2 
  3 #include <iomanip>
  4 
  5 using namespace std;
  6 
  7 template<typename T>
  8 struct TreeNode
  9 {
 10     T m_nData;
 11 
 12     TreeNode<T>* m_pLeft;
 13 
 14     TreeNode<T>* m_pRight;
 15 
 16 };
 17 
 18 
 19 template<typename T>
 20 TreeNode<T>* ConstructTree(const T* pPreTraval, const T* pInTraval, int vTreeNodeNum)
 21 {
 22     TreeNode<T> *pTreeNode =NULL;
 23 
 24     if (vTreeNodeNum > 0)
 25     {
 26         pTreeNode = new TreeNode<T>;
 27 
 28         pTreeNode->m_nData = pPreTraval[0];
 29 
 30         pTreeNode->m_pLeft = pTreeNode->m_pRight = NULL;
 31 
 32         const T * pRoot = pInTraval;
 33 
 34         const T * pLeftInTraval = NULL;
 35 
 36         const T * pRightInTraval =NULL;
 37 
 38         for (; pRoot < pInTraval + vTreeNodeNum; pRoot++)
 39         {
 40             if (*pRoot == pPreTraval[0])
 41             {
 42                 pLeftInTraval = pRoot - 1;
 43 
 44                 pRightInTraval = pRoot + 1;
 45 
 46                 break;
 47             }
 48         }
 49 
 50         if (pRoot <  pInTraval + vTreeNodeNum)
 51         {
 52             int vLeftTreeNodeNum = pLeftInTraval - pInTraval + 1;
 53 
 54             pTreeNode->m_pLeft = ConstructTree(pPreTraval + 1, pInTraval, vLeftTreeNodeNum);
 55 
 56             pTreeNode->m_pRight = ConstructTree(pPreTraval + vLeftTreeNodeNum + 1, pRightInTraval,  vTreeNodeNum - vLeftTreeNodeNum -1);
 57         }
 58         else
 59         {
 60             cout << "Invalid input" <<endl;
 61 
 62             delete pTreeNode;
 63 
 64             pTreeNode = NULL;
 65         }
 66     }
 67 
 68     return pTreeNode;
 69 }
 70 
 71 template<typename T>
 72 void PreTraval(TreeNode<T>* Tree)
 73 {
 74     if (Tree)
 75     {
 76         cout << setw(5) << Tree->m_nData;
 77 
 78         if (Tree->m_pLeft)
 79         {
 80             PreTraval(Tree->m_pLeft);
 81         }
 82 
 83         if (Tree->m_pRight)
 84         {
 85             PreTraval(Tree->m_pRight);
 86         }
 87     }
 88 }
 89 
 90 template<typename T>
 91 void InTraval(TreeNode<T>* Tree)
 92 {
 93     if (Tree)
 94     {
 95         if (Tree->m_pLeft)
 96         {
 97             InTraval(Tree->m_pLeft);
 98         }
 99 
100         cout << setw(5) << Tree->m_nData;
101 
102         if (Tree->m_pRight)
103         {
104             InTraval(Tree->m_pRight);
105         }
106     }
107 }
108 template<typename T>
109 void DestroyTree(TreeNode<T>* Tree)
110 {
111     if (Tree)
112     {
113         if (Tree->m_pLeft)
114         {
115             DestroyTree(Tree->m_pLeft);
116         }
117         if (Tree->m_pRight)
118         {
119             DestroyTree(Tree->m_pRight);
120         }
121 
122         delete Tree;
123 
124         Tree = NULL;
125     }
126 }
127 void main()
128 {
129     const int treeNodeNum = 8;
130 
131     /*int preTraval[] = {1, 2, 4, 7, 3, 5, 6, 8};
132 
133     int inTraval[] = {4, 7, 2, 1, 5, 3, 8, 6};
134 
135     TreeNode<int> * pTree = NULL;
136 
137     pTree = ConstructTree(preTraval, inTraval, treeNodeNum);
138 
139     PreTraval(pTree);
140 
141     cout << endl;
142 
143     InTraval(pTree);
144 
145     cout << endl;
146 
147     DestroyTree(pTree);
148 
149     pTree = NULL;*/
150 
151 
152 
153     char preTraval[] = {'a', 'b', 'd', 'h', 'c', 'f', 'g', 'i'};
154 
155     char inTraval[] = {'d', 'h', 'b', 'a', 'f', 'c', 'i', 'g'};
156 
157     TreeNode<char> * pTree = NULL;
158 
159     pTree = ConstructTree(preTraval, inTraval, treeNodeNum);
160 
161     PreTraval(pTree);
162 
163     cout << endl;
164 
165     InTraval(pTree);
166 
167     cout << endl;
168 
169     DestroyTree(pTree);
170 
171     pTree = NULL;
172 
173 
174 
175     system("pause");
176 
177     return;
178 
179 }

模板类版本

  1 #ifndef _TREE_
  2 
  3 #define _TREE_
  4 
  5 #include <iostream>
  6 
  7 #include <iomanip>
  8 
  9 using namespace std;
 10 
 11 template<typename T>
 12 struct TreeNode
 13 {
 14     T m_nData;
 15 
 16     TreeNode<T>* m_pLeft;
 17 
 18     TreeNode<T>* m_pRight;
 19 };
 20 
 21 template<typename T>
 22 class Tree
 23 {
 24 
 25 public:
 26     Tree()
 27     {
 28         m_pTree = NULL;
 29     }
 30 
 31     ~Tree()
 32     {
 33         DestroyTree(m_pTree);
 34     }
 35     
 36     void PreTraval(TreeNode<T> *m_pTree);
 37     
 38     void InTraval(TreeNode<T> *m_pTree);
 39 
 40     void DestroyTree(TreeNode<T> *m_pTree);
 41     
 42     TreeNode<T>* GetTreeRoot();
 43 
 44     void CreateBinaryTree(const T* pPreTraval, const T* pInTraval, int vTreeNodeNum);
 45 
 46 private:
 47 
 48     TreeNode<T>* ConstructTree(const T* pPreTraval, const T* pInTraval, int vTreeNodeNum);
 49 
 50 private:
 51 
 52     TreeNode<T> *m_pTree;
 53 
 54 };
 55 
 56 template<typename T>
 57 void Tree<T>::CreateBinaryTree(const T* pPreTraval, const T* pInTraval, int vTreeNodeNum)
 58 {
 59     m_pTree = ConstructTree(pPreTraval, pInTraval, vTreeNodeNum);
 60 }
 61 
 62 template<typename T>
 63 TreeNode<T>* Tree<T>::ConstructTree(const T* pPreTraval, const T* pInTraval, int vTreeNodeNum)
 64 {
 65     TreeNode<T> *pTreeNode =NULL;
 66 
 67     if (vTreeNodeNum > 0)
 68     {
 69         pTreeNode = new TreeNode<T>;
 70 
 71         pTreeNode->m_nData = pPreTraval[0];
 72 
 73         pTreeNode->m_pLeft = pTreeNode->m_pRight = NULL;
 74 
 75         const T * pRoot = pInTraval;
 76 
 77         const T * pLeftInTraval = NULL;
 78 
 79         const T * pRightInTraval =NULL;
 80 
 81         for (; pRoot < pInTraval + vTreeNodeNum; pRoot++)
 82         {
 83             if (*pRoot == pPreTraval[0])
 84             {
 85                 pLeftInTraval = pRoot - 1;
 86 
 87                 pRightInTraval = pRoot + 1;
 88 
 89                 break;
 90             }
 91         }
 92 
 93         if (pRoot <  pInTraval + vTreeNodeNum)
 94         {
 95             int vLeftTreeNodeNum = pLeftInTraval - pInTraval + 1;
 96 
 97             pTreeNode->m_pLeft = ConstructTree(pPreTraval + 1, pInTraval, vLeftTreeNodeNum);
 98 
 99             pTreeNode->m_pRight = ConstructTree(pPreTraval + vLeftTreeNodeNum + 1, pRightInTraval,  vTreeNodeNum - vLeftTreeNodeNum -1);
100         }
101         else
102         {
103             cout << "Invalid input" <<endl;
104 
105             delete pTreeNode;
106 
107             pTreeNode = NULL;
108         }
109     }
110 
111     return pTreeNode;
112 }
113 
114 template<typename T>
115 void Tree<T>::PreTraval(TreeNode<T> *m_pTree)
116 {
117     if (m_pTree)
118     {
119         cout << setw(5) << m_pTree->m_nData;
120 
121         if (m_pTree->m_pLeft)
122         {
123             PreTraval(m_pTree->m_pLeft);
124         }
125 
126         if (m_pTree->m_pRight)
127         {
128             PreTraval(m_pTree->m_pRight);
129         }
130     }
131 }
132 
133 template<typename T>
134 void Tree<T>::InTraval(TreeNode<T> *m_pTree)
135 {
136     if (m_pTree)
137     {
138         if (m_pTree->m_pLeft)
139         {
140             InTraval(m_pTree->m_pLeft);
141         }
142 
143         cout << setw(5) << m_pTree->m_nData;
144 
145         if (m_pTree->m_pRight)
146         {
147             InTraval(m_pTree->m_pRight);
148         }
149     }
150 }
151 
152 template<typename T>
153 void Tree<T>::DestroyTree(TreeNode<T> *m_pTree)
154 {
155     if (m_pTree)
156     {
157         if (m_pTree->m_pLeft)
158         {
159             DestroyTree(m_pTree->m_pLeft);
160         }
161         if (m_pTree->m_pRight)
162         {
163             DestroyTree(m_pTree->m_pRight);
164         }
165 
166         delete m_pTree;
167 
168         m_pTree = NULL;
169     }
170 }
171 
172 template<typename T>
173 TreeNode<T>* Tree<T>::GetTreeRoot()
174 {
175     return m_pTree;
176 }
177 
178 #endif

View Code

主函数

 1 #include "Tree.h"
 2 
 3 int main()
 4 {
 5     const int treeNodeNum = 8;
 6 
 7     int preTraval[] = {1, 2, 4, 7, 3, 5, 6, 8};
 8 
 9     int inTraval[] = {4, 7, 2, 1, 5, 3, 8, 6};
10 
11     Tree<int> binaryTree;
12 
13     TreeNode<int> *binaryTreeRoot = NULL;
14 
15     binaryTree.CreateBinaryTree(preTraval, inTraval,treeNodeNum);
16 
17     binaryTreeRoot = binaryTree.GetTreeRoot();
18 
19     binaryTree.PreTraval(binaryTreeRoot);
20 
21     cout << endl;
22 
23     binaryTree.InTraval(binaryTreeRoot);
24 
25     cout << endl;
26 
27     system("pause");
28 
29     return 0;
30 
31 }

View Code

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原文地址：https://www.cnblogs.com/alpha19881007/p/201309121043_byalpha.html