关于二叉树

1、二叉树的建立

#include<iostream>#include<stdlib.h>using namespace std;typedef struct BTNode{char data;struct BTNode *lchild;struct BTNode *rchild;}BTNode;void createBTree(BTNode *&root){char c;    cin>>c;fflush(stdin);if(c=='#'){root=NULL;}else{root=(BTNode *)malloc(sizeof(BTNode));root->data=c;cout<<"please print the left child"<<endl;createBTree(root->lchild);cout<<"please print the right child"<<endl;createBTree(root->rchild);}}int main(){BTNode *root;createBTree(root);}

2、二叉树的先序中序后序递归遍历

//二叉树的先序递归遍历void  preorderRaversal(BTNode *root){if(root){cout<<root->data<<" ";preorderRaversal(root->lchild);preorderRaversal(root->rchild);}}//二叉树的中序递归遍历void inorderRaversal(BTNode *root){if(root){inorderRaversal(root->lchild);cout<<root->data<<" ";inorderRaversal(root->rchild);}}//二叉树的后续递归遍历void postorderRaversal(BTNode *root){if(root){postorderRaversal(root->lchild);postorderRaversal(root->rchild);cout<<root->data<<" ";}}

3、二叉树的递归求深

int getDepth(BTNode *root){int LD,RD;if(!root)return 0;else{LD=getDepth(root->lchild);RD=getDepth(root->rchild);return (LD>RD ? LD:RD)+1;}}

4、二叉树的先序非递归遍历

   对任一节点p

   1）访问p节点，并将p节点入栈

   2）判断p节点的左孩子是否为空，若为空，则取栈顶节点并进行出栈操作，并将p右孩子置为当前的节点p，循环至1），若不为空，则将p的左孩子置为p

   3）直到p为NULL，并且栈为空

//二叉树的先序非递归遍历void  preorderRaversal2(BTNode *root){const stack<BTNode>::size_type stackSize=100;  //给定栈的大小stack<BTNode> BTNodeStack;   //定义一个空栈BTNode *p=root;while(p||!BTNodeStack.empty()){while(p){cout<<p->data<<" "; BTNodeStack.push(*p);p=p->lchild;}if(!BTNodeStack.empty()){p=&BTNodeStack.top();BTNodeStack.pop();p=p->rchild;}}}

5、二叉树的中序非递归遍历

//中序非递归遍历void inorderRaversal2(BTNode *root){const stack<BTNode>::size_type stackSize=100;  //给定栈的大小stack<BTNode> BTNodeStack;   //定义一个空栈BTNode *p=root;while(p||!BTNodeStack.empty()){while(p){BTNodeStack.push(*p);p=p->lchild;}if(!BTNodeStack.empty()){p=&BTNodeStack.top();BTNodeStack.pop();cout<<p->data<<" ";p=p->rchild;}}}

6、二叉树的后序非递归遍历

typedef enum{L,R} tagtype;typedef struct  {BTNode *p;tagtype tag;}stacknode;void postorderRaversal2(BTNode *root){const stack<stacknode>::size_type stackSize=100;  //给定栈的大小stack<stacknode> BTNodeStack;   //定义一个空栈BTNode *p=root;stacknode x;do {while (p){x.p=p;x.tag=L;BTNodeStack.push(x);p=p->lchild;}while(!BTNodeStack.empty()&&BTNodeStack.top().tag==R){x=BTNodeStack.top();BTNodeStack.pop();p=x.p;cout<<p->data<<" ";}if(!BTNodeStack.empty()){BTNodeStack.top().tag=R;p=BTNodeStack.top().p->rchild;}}while(!BTNodeStack.empty());}