#include<iostream>
#include<stdlib.h>
#define maxsize 100
using namespace std;
typedef struct BTNode{
char val;
BTNode *lchild, *rchild;
}*BiTNode;
void CreateTree(BTNode *&root){
char c;
cin >> c;
if(c == '#')
root = NULL;
else{
root = (BTNode *) malloc(sizeof(BTNode));
if(!root){
cerr << "No More Memory!" << endl;
exit(-1);
}
root->val = c;
CreateTree(root->lchild);
CreateTree(root->rchild);
}
}
void PreOrderRecursion(BTNode *root){
if(root){
cout << root->val << " ";
PreOrderRecursion(root->lchild);
PreOrderRecursion(root->rchild);
}
}
void PreOrderNoRecursion(BTNode *root){
if(!root){
cout << "Root is NULL!" << endl;
return;
}
BTNode* stack[maxsize]; //模拟一个栈
int top = -1; //栈顶指针
stack[++top] = root;
while(top != -1){
BTNode *p = stack[top--];
cout << p->val << " ";
if(p->rchild) //由于左子树先被访问,则右子树应该先入栈
stack[++top] = p->rchild;
if(p->lchild)
stack[++top] = p->lchild;
}
}
void InOrderRecursion(BTNode *root){
if(root){
InOrderRecursion(root->lchild);
cout << root->val << " ";
InOrderRecursion(root->rchild);
}
}
void InOrderNoRecursion(BTNode *root){
if(!root){
cout << "Root is NULL!" << endl;
return;
}
BTNode* stack[maxsize];
int top = -1;
BTNode *p = root;
while(top != -1 || p != NULL){
while(p){
stack[++top] = p;
p = p->lchild;
}
//从根节点一直往左子树遍历,如果没有左子树
//打印这个节点,往右节点移动
p = stack[top--];
cout << p->val << " ";
p = p->rchild;
}
}
void PostOrderRecursion(BTNode *root){
if(root){
PostOrderRecursion(root->lchild);
PostOrderRecursion(root->rchild);
cout << root->val << " ";
}
}
void PostOrderNoRecursion(BTNode *root){
if(!root){
cout << "Root is NULL!" << endl;
return;
}
BTNode* stack1[maxsize]; int top1 = -1;
BTNode* stack2[maxsize]; int top2 = -1;
//首先把根节点如stack1
stack1[++top1] = root;
while(top1 != -1){
BTNode *p = stack1[top1--];
stack2[++top2] = p;
if(p->lchild)
stack1[++top1] = p->lchild;
if(p->rchild)
stack1[++top1] = p->rchild;
}
//此时倒序输出stack2即为后序遍历的序列
while(top2 != -1){
BTNode *p = stack2[top2--];
cout << p->val << " ";
}
}
int main(){
BTNode *root;
CreateTree(root);
/**
test code
*/
return 0;
}
Non-recursive binary tree traversal implemented in C ++
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Origin www.cnblogs.com/dotdashdotdash/p/11863592.html
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