平衡二叉树的插入过程: http://www.cnblogs.com/hujunzheng/p/4665451.html
对于二叉平衡树的删除采用的是二叉排序树删除的思路:
假设被删结点是*p,其双亲是*f,不失一般性,设*p是*f的左孩子,下面分三种情况讨论:
⑴ 若结点*p是叶子结点,则只需修改其双亲结点*f的指针即可。
⑵ 若结点*p只有左子树PL或者只有右子树PR,则只要使PL或PR 成为其双亲结点的左子树即可。
⑶ 若结点*p的左、右子树均非空,先找到*p的中序前趋结点*s(注意*s是*p的左子树中的最右下的结点,它的右链域为空),然后有两种做法:
① 令*p的左子树直接链到*p的双亲结点*f的左链上,而*p的右子树链到*p的中序前趋结点*s的右链上。
② 以*p的中序前趋结点*s代替*p(即把*s的数据复制到*p中),将*s的左子树链到*s的双亲结点*q的左(或右)链上。
注:leftBalance_del 和 rightBalance_del方法是在删除节点时对左子树和右子树的平衡调整,leftBalance 和 rightBalance方法是在插入节点是对左右子树的平衡调整。 在具体调整的时候,和插入式调整时运用同样的分类方法,这里介绍一种情况,如下图所示(代码部分见代码中的提示)
#include<iostream> #include<cstring> #include<string> #include<queue> #include<map> #include<cstdio> #define LH 1 //左高 #define EH 0 //等高 #define RH -1 //右高 using namespace std;template <typename ElemType> class BSTNode{public:ElemType data;//节点的数据 int bf;//节点的平衡因子BSTNode *child[2];BSTNode(){child[0] = NULL;child[1] = NULL;} };typedef BSTNode<string> BSTnode, *BSTree;template <typename ElemType> class AVL{public:BSTNode<ElemType> *T;void buildT();void outT(BSTNode<ElemType> *T);void deleteAVL(BSTNode<ElemType>* &T, ElemType key, bool &shorter);bool insertAVL(BSTNode<ElemType>* &T, ElemType key, bool &taller); private:void deleteNode(BSTNode<ElemType>* T, BSTNode<ElemType>* &s, BSTNode<ElemType>* p, bool flag, bool &shorter);void rotateT(BSTNode<ElemType>* &o, int x);//子树的左旋或者右旋void leftBalance(BSTNode<ElemType>* &o);void rightBalance(BSTNode<ElemType>* &o);void leftBalance_del(BSTNode<ElemType>* &o);void rightBalance_del(BSTNode<ElemType>* &o); };template <typename ElemType> void AVL<ElemType>::rotateT(BSTNode<ElemType>* &o, int x){BSTNode<ElemType>* k = o->child[x^1];o->child[x^1] = k->child[x];k->child[x] = o;o = k; }template <typename ElemType> void AVL<ElemType>::outT(BSTNode<ElemType> *T){if(!T) return;cout<<T->data<<" ";outT(T->child[0]);outT(T->child[1]); }template <typename ElemType> void AVL<ElemType>::buildT(){T = NULL;ElemType key;while(cin>>key){if(key==0) break;bool taller = false;insertAVL(T, key, taller);} }template <typename ElemType> void AVL<ElemType>::deleteNode(BSTNode<ElemType>* T, BSTNode<ElemType>* &s, BSTNode<ElemType>* p, bool flag, bool &shorter){if(flag){flag = false;deleteNode(T, s->child[0], s, flag, shorter);if(shorter){switch(s->bf){case LH:s->bf = EH;shorter = false;break; case EH:s->bf = RH;shorter = true;break; case RH:rightBalance_del(s);shorter = false;break;}}} else {if(s->child[1]==NULL){T->data = s->data;BSTNode<ElemType>* ss = s; if(p != T){p->child[1] = s->child[0];} else {p->child[0] = s->child[0];}delete ss;//s是引用类型,不能delete s shorter = true; return ;}deleteNode(T, s->child[1], s, flag, shorter);if(shorter){switch(s->bf){case LH://这是上面配图的情况leftBalance_del(s);shorter = false; break; case EH:s->bf = LH;shorter = true;break; case RH:s->bf = EH;shorter = false;break;}} } } template <typename ElemType> bool AVL<ElemType>::insertAVL(BSTNode<ElemType>* &T, ElemType key, bool &taller){if(!T){//插入新的节点,taller=true 那么树的高度增加 T = new BSTNode<ElemType>();T->data = key;T->bf = EH;taller = true;} else {if(T->data == key){taller = false;return false;}if(T->data > key){//向T的左子树进行搜索并插入 if(!insertAVL(T->child[0], key, taller)) return false;if(taller){// switch(T->bf){case LH://此时左子树的高度高,左子树上又插入了一个节点,失衡,需要进行调整 leftBalance(T);taller = false;//调整之后高度平衡 break; case EH:T->bf = LH;taller = true;break; case RH:T->bf = EH;taller = false; break;}}} if(T->data < key) {//向T的右子树进行搜索并插入 if(!insertAVL(T->child[1], key, taller)) return false;switch(T->bf){case LH:T->bf = EH;taller = false; break; case EH:T->bf = RH;taller = true;break; case RH:rightBalance(T); taller = false; break;}}}return true; }template <typename ElemType> void AVL<ElemType>::deleteAVL(BSTNode<ElemType>* &T, ElemType key, bool &shorter){if(T->data == key){BSTNode<ElemType>*q, s; if(!T->child[1]){//右子树为空,然后重接其左子树 q = T;T = T->child[0];shorter = true;//树变矮了 delete q;} else if(!T->child[0]){//左子树为空,重接其右子树 q = T;T = T->child[1];shorter = true;//树变矮了 delete q;} else {//左右子树都非空 ,也就是第三种情况 deleteNode(T, T, NULL, true, shorter);shorter = true;} } else if(T->data > key) {//左子树 deleteAVL(T->child[0], key, shorter);if(shorter){switch(T->bf){case LH:T->bf = EH; shorter = false;break;case RH:rightBalance_del(T);shorter = false;break;case EH:T->bf = RH;shorter = true;break;}}} else if(T->data < key){//右子树 deleteAVL(T->child[1], key, shorter);if(shorter){switch(T->bf){case LH://这是上面配图的情况leftBalance_del(T);shorter = false;
break;case RH:T->bf = EH;shorter = false; break;case EH:T->bf = LH;shorter = true;break;}}} }template <typename ElemType> void AVL<ElemType>::leftBalance(BSTNode<ElemType>* &T){BSTNode<ElemType>* lchild = T->child[0];switch(lchild->bf){//检查T的左子树的平衡度,并作相应的平衡处理 case LH://新节点 插入到 T的左孩子的左子树上,需要对T节点做单旋(右旋)处理 T->bf = lchild->bf = EH; rotateT(T, 1);break;case RH://新节点 插入到 T的左孩子的右子树上,需要做双旋处理 1.对lchild节点进行左旋,2.对T节点进行右旋 BSTNode<ElemType>* rdchild = lchild->child[1];switch(rdchild->bf){//修改 T 及其左孩子的平衡因子 case LH: T->bf = RH; lchild->bf = EH; break;case EH: T->bf = lchild->bf = EH; break;//发生这种情况只能是 rdchild无孩子节点case RH: T->bf = EH; lchild->bf = LH; break; }rdchild->bf = EH; rotateT(T->child[0], 0);//不要写成 rotateT(lc, 0);//这样的话T->lchild不会改变 rotateT(T, 1);break;} }template <typename ElemType> void AVL<ElemType>::rightBalance(BSTNode<ElemType>* &T){BSTNode<ElemType>* rchild = T->child[1];switch(rchild->bf){//检查T的左子树的平衡度,并作相应的平衡处理 case RH://新节点 插入到 T的右孩子的右子树上,需要对T节点做单旋(左旋)处理 T->bf = rchild->bf = EH; rotateT(T, 0);break;case LH://新节点 插入到 T的右孩子的左子树上,需要做双旋处理 1.对rchild节点进行右旋,2.对T节点进行左旋 BSTNode<ElemType>* ldchild = rchild->child[0];switch(ldchild->bf){//修改 T 及其右孩子的平衡因子 case LH: T->bf = EH; rchild->bf = RH; break;case EH: T->bf = rchild->bf = EH; break;//发生这种情况只能是 ldchild无孩子节点 case RH: T->bf = LH; rchild->bf = EH; break; }ldchild->bf = EH; rotateT(T->child[1], 1);rotateT(T, 0);break;} }template <typename ElemType> void AVL<ElemType>::leftBalance_del(BSTNode<ElemType>* &T){BSTNode<ElemType>* lchild = T->child[0];switch(lchild->bf){ case LH:T->bf = EH; lchild->bf = EH; rotateT(T, 1);break;case EH:T->bf = LH;lchild->bf = EH; rotateT(T, 1);break;case RH://这是上面配图的情况BSTNode<ElemType>* rdchild = lchild->child[1];switch(rdchild->bf){ case LH:T->bf = RH;lchild->bf = rdchild->bf = EH;break;case EH:rdchild->bf = T->bf = lchild->bf = EH; break;case RH:T->bf = rdchild->bf = EH;lchild->bf = LH; break;}rotateT(T->child[0], 0);rotateT(T, 1);break;} }template <typename ElemType> void AVL<ElemType>::rightBalance_del(BSTNode<ElemType>* &T){BSTNode<ElemType>* rchild = T->child[1];BSTNode<ElemType>* ldchild = rchild->child[0];switch(rchild->bf){ case LH:switch(ldchild->bf){ case LH:ldchild->bf = T->bf = EH; rchild->bf = RH;break;case EH:ldchild->bf = T->bf = rchild->bf = EH; break;case RH:rchild->bf = T->bf = EH; ldchild->bf = LH;break;}rotateT(T->child[1], 1);rotateT(T, 0);break;case EH://outT(this->T);e EH:T->bf = RH;rchild->bf = EH; rotateT(T, 0);break;case RH:T->bf = EH; rchild->bf = EH; rotateT(T, 0);break;} }int main(){AVL<int> avl;avl.buildT();cout<<"平衡二叉树先序遍历如下:"<<endl;avl.outT(avl.T);cout<<endl;bool shorter = false;avl.deleteAVL(avl.T, 24, shorter);avl.outT(avl.T);return 0; } /*13 24 37 90 53 013 24 37 90 53 12 26 0 */