C++ 實現 AVL 樹程式


AVL 樹是一種自平衡二叉搜尋樹,其中所有節點的左右子樹的高度差不能超過 1。

樹旋轉是一種不改變元素順序的操作,它改變了 AVL 樹的結構。它將一個節點向上移動,另一個節點向下移動。它用於改變樹的形狀,並透過將較小的子樹向下移動,較大的子樹向上移動來降低樹的高度,從而提高許多樹操作的效能。旋轉的方向取決於樹節點移動到的方向,也有人說它取決於哪個子節點取代了根節點的位置。這是一個用 C++ 實現 AVL 樹的程式。

函式描述

height(avl *):計算給定 AVL 樹的高度。

difference(avl *):計算給定樹的子樹高度差。

avl *rr_rotat(avl *):右-右旋轉是右旋轉後接右旋轉的組合。

avl *ll_rotat(avl *):左-左旋轉是左旋轉後接左旋轉的組合。

avl *lr_rotat(avl*):左-右旋轉是左旋轉後接右旋轉的組合。

avl *rl_rotat(avl *):它是右旋轉後接左旋轉的組合。

avl * balance(avl *): 透過獲取平衡因子來對樹執行平衡操作

avl * insert(avl*, int):執行插入操作。使用此函式在樹中插入值。

show(avl*, int): 顯示樹的值。

inorder(avl *):以中序方式遍歷樹。

preorder(avl *):以先序方式遍歷樹。

postorder(avl*):以後序方式遍歷樹。

示例程式碼

#include<iostream>
#include<cstdio>
#include<sstream>
#include<algorithm>
#define pow2(n) (1 << (n))
using namespace std;
struct avl {
   int d;
   struct avl *l;
   struct avl *r;
}*r;
class avl_tree {
   public:
      int height(avl *);
      int difference(avl *);
      avl *rr_rotat(avl *);
      avl *ll_rotat(avl *);
      avl *lr_rotat(avl*);
      avl *rl_rotat(avl *);
      avl * balance(avl *);
      avl * insert(avl*, int);
      void show(avl*, int);
      void inorder(avl *);
      void preorder(avl *);
      void postorder(avl*);
      avl_tree() {
         r = NULL;
      }
};
int avl_tree::height(avl *t) {
   int h = 0;
   if (t != NULL) {
      int l_height = height(t->l);
      int r_height = height(t->r);
      int max_height = max(l_height, r_height);
      h = max_height + 1;
   }
   return h;
}
int avl_tree::difference(avl *t) {
   int l_height = height(t->l);
   int r_height = height(t->r);
   int b_factor = l_height - r_height;
   return b_factor;
}
avl *avl_tree::rr_rotat(avl *parent) {
   avl *t;
   t = parent->r;
   parent->r = t->l;
   t->l = parent;
   cout<<"Right-Right Rotation";
   return t;
}
avl *avl_tree::ll_rotat(avl *parent) {
   avl *t;
   t = parent->l;
   parent->l = t->r;
   t->r = parent;
   cout<<"Left-Left Rotation";
   return t;
}
avl *avl_tree::lr_rotat(avl *parent) {
   avl *t;
   t = parent->l;
   parent->l = rr_rotat(t);
   cout<<"Left-Right Rotation";
   return ll_rotat(parent);
}
avl *avl_tree::rl_rotat(avl *parent) {
   avl *t;
   t = parent->r;
   parent->r = ll_rotat(t);
   cout<<"Right-Left Rotation";
   return rr_rotat(parent);
}
avl *avl_tree::balance(avl *t) {
   int bal_factor = difference(t);
   if (bal_factor > 1) {
      if (difference(t->l) > 0)
         t = ll_rotat(t);
      else
         t = lr_rotat(t);
   } else if (bal_factor < -1) {
      if (difference(t->r) > 0)
         t = rl_rotat(t);
      else
         t = rr_rotat(t);
   }
   return t;
}
avl *avl_tree::insert(avl *r, int v) {
   if (r == NULL) {
      r = new avl;
      r->d = v;
      r->l = NULL;
      r->r = NULL;
      return r;
   } else if (v< r->d) {
      r->l = insert(r->l, v);
      r = balance(r);
   } else if (v >= r->d) {
      r->r = insert(r->r, v);
      r = balance(r);
   } return r;
}
void avl_tree::show(avl *p, int l) {
   int i;
   if (p != NULL) {
      show(p->r, l+ 1);
      cout<<" ";
      if (p == r)
         cout << "Root -> ";
      for (i = 0; i < l&& p != r; i++)
         cout << " ";
         cout << p->d;
         show(p->l, l + 1);
   }
}
void avl_tree::inorder(avl *t) {
   if (t == NULL)
      return;
      inorder(t->l);
      cout << t->d << " ";
      inorder(t->r);
}
void avl_tree::preorder(avl *t) {
   if (t == NULL)
      return;
      cout << t->d << " ";
      preorder(t->l);
      preorder(t->r);
}
void avl_tree::postorder(avl *t) {
   if (t == NULL)
      return;
      postorder(t ->l);
      postorder(t ->r);
      cout << t->d << " ";
}
int main() {
   int c, i;
   avl_tree avl;
   while (1) {
      cout << "1.Insert Element into the tree" << endl;
      cout << "2.show Balanced AVL Tree" << endl;
      cout << "3.InOrder traversal" << endl;
      cout << "4.PreOrder traversal" << endl;
      cout << "5.PostOrder traversal" << endl;
      cout << "6.Exit" << endl;
      cout << "Enter your Choice: ";
      cin >> c;
      switch (c) {
         case 1:
            cout << "Enter value to be inserted: ";
            cin >> i;
            r = avl.insert(r, i);
         break;
         case 2:
            if (r == NULL) {
               cout << "Tree is Empty" << endl;
               continue;
            }
            cout << "Balanced AVL Tree:" << endl;
            avl.show(r, 1);
            cout<<endl;
         break;
         case 3:
            cout << "Inorder Traversal:" << endl;
            avl.inorder(r);
            cout << endl;
         break;
         case 4:
            cout << "Preorder Traversal:" << endl;
            avl.preorder(r);
            cout << endl;
         break;
         case 5:
            cout << "Postorder Traversal:" << endl;
            avl.postorder(r);
            cout << endl;
         break;
         case 6:
            exit(1);
         break;
         default:
            cout << "Wrong Choice" << endl;
      }
   }
   return 0;
}

輸出

1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 13
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 10
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 15
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 5
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 11
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 4
Left-Left Rotation1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 8
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 16
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 3
Inorder Traversal:
4 5 8 10 11 13 15 16
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 4
Preorder Traversal:
10 5 4 8 13 11 15 16
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 5
Postorder Traversal:
4 8 5 11 16 15 13 10
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 14
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 3
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 7
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 9
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 1
Enter value to be inserted: 52
Right-Right Rotation
1.Insert Element into the tree
2.show Balanced AVL Tree
3.InOrder traversal
4.PreOrder traversal
5.PostOrder traversal
6.Exit
Enter your Choice: 6

更新於: 2019-07-30

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