Add extention about how to creat a binary tree from pre-order & in-order.

树和二叉树/BinaryTree.h

+#pragma once
+
 //Include Liberary.
 #include <iostream>
 #include <stack>
@@ -42,11 +44,58 @@ void CreatBiTree_Rec(BiTree &root)
 //Loop to creat binary tree.
 void CreatBiTree_Loop(BiTree &root)
 {
+    char c;
     stack<BiTree> BiStack;
 
-    while (true)
+    root = new BiNode;
+    BiNode *p = root;
+    bool IsRight = false;
+
+    //Define a pointer to do many thing.
+    p->data = getchar();
+    //Push in.
+    BiStack.push(p);
+
+    while (c = getchar())
     {
+        switch (c)
+        {
+        case '#':
+            //If null stack then end.
+            if (BiStack.empty())
+            {
+                return;
+            }
+            //pB revoke.
+            p = BiStack.top();
+            BiStack.pop();
+            IsRight = true;
+            break;
+        default:
+            if (IsRight)
+            {
+                p->RightChild = new BiNode;
+                p = p->RightChild;
+            }
+            else
+            {
+                p->LeftChild = new BiNode;
+                p = p->LeftChild;
+            }
+
+            //Tag the pB.
+            p->data = c;
+            p->LeftChild = p->RightChild = NULL;
+
+            //Push in.
+            BiStack.push(p);
+
+            IsRight = false;
+            break;
+        }
     }
+
+    return;
 }
 
 enum Type

树和二叉树/Extention.h

+#pragma once
+
+#include "BinaryTree.h"
+#include <string>
+
+void UnionPreIn(string Pre, string In, BiTree &root)
+{
+    //Pre order:ABDECFGH
+    //In order:DEBAGFCH
+    root = new BiNode;
+    root->data = Pre[0];
+    string left, right;
+
+    int rootPos = In.find(Pre[0]);
+    left = In.substr(0, rootPos);
+    right = In.substr(rootPos + 1, In.length());
+
+    int lLength = left.length();
+    int rLength = right.length();
+
+    root->LeftChild = root->RightChild = NULL;
+
+    if (lLength != 0)
+    {
+        cout << "LEFT" << endl;
+        cout << '\t' << Pre.substr(1, lLength) << " " << left << endl;
+
+        root->LeftChild = new BiNode;
+        cout << root->data << "l" << Pre.substr(1, lLength)[0] << endl;
+        root->LeftChild->data = Pre.substr(1, lLength)[0];
+        UnionPreIn(Pre.substr(1, lLength), left, root->LeftChild);
+    }
+
+    if (rLength != 0)
+    {
+        cout << "RIGHT" << endl;
+        cout << '\t' << Pre.substr(Pre.length() - rLength, Pre.length()) << " " << right << endl;
+
+        root->RightChild = new BiNode;
+        cout << root->data << "r" << Pre.substr(Pre.length() - rLength, Pre.length())[0] << endl;
+        root->RightChild->data = Pre.substr(Pre.length() - rLength, Pre.length())[0];
+        UnionPreIn(Pre.substr(Pre.length() - rLength, Pre.length()), right, root->RightChild);
+    }
+}
\ No newline at end of file

树和二叉树/main.cpp

 #include "BinaryTree.h"
+#include "Extention.h"
 
 int main()
 {
@@ -8,8 +9,11 @@ int main()
     //Pre order:ABDECFGH
     //In order:DEBAGFCH
     //Post order:EDBGFHCA
+
+    /*
     cout << "Input ebt:" << endl;
-    CreatBiTree_Rec(root);
+    //CreatBiTree_Rec(root);
+    CreatBiTree_Loop(root);
 
     cout << "Pre order:" << endl;
     DisplayBiTree_Stack(root, Pre);
@@ -28,6 +32,15 @@ int main()
     cout << endl;
     DisplayBiTree(root, Post);
     cout << endl;
+*/
+    UnionPreIn("ABDECFGH", "DEBAGFCH", root);
+    cout << endl;
+    DisplayBiTree(root, Pre);
+    cout << endl;
+    DisplayBiTree(root, In);
+    cout << endl;
+    DisplayBiTree(root, Post);
+    cout << endl;
 
     return 0;
 }
\ No newline at end of file