二叉树的建立与遍历

来源：互联网发布：java导出文件到桌面编辑：程序博客网时间：2024/06/05 14:42
二叉树的建立与遍历：
#include <iostream>#include<string>#include <vector>#include<algorithm>#include <stack>#include <queue>using namespace std;//二叉树的建立与遍历typedef struct TreeNode{ char val; struct TreeNode* left; struct TreeNode* right;}TreeNode;void CreateTree(TreeNode* &root){char data;cin>>data;if(data=='#') root=NULL;else{ root=new TreeNode;     root->val=data; CreateTree(root->left); CreateTree(root->right);}}void PreTree(TreeNode* root){if(root){cout<<root->val<<" ";PreTree(root->left);PreTree(root->right);}}void InTree(TreeNode* root){if(root){InTree(root->left);cout<<root->val<<" ";InTree(root->right);}}void PostTree(TreeNode* root){if(root){PostTree(root->left);PostTree(root->right);cout<<root->val<<" ";}}/* 先序遍历(非递归)    思路：访问T->data后，将T入栈，遍历左子树；遍历完左子树返回时，栈顶元素应为T，出栈，再先序遍历T的右子树。 */  void PreTree2(TreeNode* root){stack<TreeNode*>s;while(!s.empty()||root){ if(root) {  s.push(root);  cout<<root->val<<" ";  root=root->left; } else {  root=s.top();  s.pop();  root=root->right; }}}/* 中序遍历(非递归)    思路：T是要遍历树的根指针，中序遍历要求在遍历完左子树后，访问根，再遍历右子树。          先将T入栈，遍历左子树；遍历完左子树返回时，栈顶元素应为T，出栈，访问T->data，再中序遍历T的右子树。 */  void InTree2(TreeNode* root){stack<TreeNode*>s;while(!s.empty()||root){if(root){ s.push(root); root=root->left;}else{ root=s.top(); cout<<root->val<<" "; s.pop(); root=root->right;}}}void PostTree2(TreeNode* root){stack<TreeNode*>s;TreeNode* preroot=NULL;while(!s.empty()||root){ while(root)//一直左走到底 {  s.push(root);  root=root->left; } root=s.top(); if(root->right==NULL||root==preroot)  // 当前节点的右孩子如果为空或者已经被访问，则访问当前节点     {  cout<<root->val<<" ";  s.pop();  root=NULL; } else {  preroot=root;  root=root->right; } }}//层次遍历void LevelTree(TreeNode* root){queue<TreeNode*> q;if(root)q.push(root);while(!q.empty()){ root=q.front(); cout<<root->val<<" "; q.pop(); if(root->left) q.push(root->left); if(root->right)q.push(root->right);}}int main(){ TreeNode* root; CreateTree(root); cout<<"先序遍历递归："<<endl; PreTree(root); cout<<endl; cout<<"中序遍历递归："<<endl; InTree(root); cout<<endl; cout<<"后序遍历递归："<<endl; PostTree(root); cout<<endl; cout<<"先序遍历非递归："<<endl; PreTree2(root); cout<<endl; cout<<"中序遍历非递归："<<endl; InTree2(root); cout<<endl; cout<<"后序遍历非递归："<<endl; PostTree2(root); cout<<endl; cout<<"层次遍历非递归："<<endl; LevelTree(root); cout<<endl; return 0;}
0 0