先序遍历和中序遍历非递归代码：
#include <iostream>
#include <vector>
using namespace std;typedef struct BinaryTree
{
int data;
struct BinaryTree *rchild, *lchild;
}BinaryTree;int createBinaryTree( BinaryTree * &T) //必须用引用 因为内存是在函数里面分配的
{
int ch;
scanf("%d", &ch);if(ch != 0)
{
T = (BinaryTree *)malloc(sizeof(BinaryTree));
T->data = ch;
createBinaryTree(T->lchild);
createBinaryTree(T->rchild);
}
else
{
T = NULL;
}
return 0;
}int visit(int data)
{
printf("%d ", data);
return 0;
}int PreOrderTraverse(BinaryTree T) //先序遍历
{
BinaryTree* p;
vector<BinaryTree *> Stack;
Stack.push_back(&T);
while(!Stack.empty())
{
while((p = Stack.back()) != NULL)
{
visit(p->data);
Stack.push_back(p->lchild);
}
Stack.pop_back();
if(!Stack.empty())
{
p = Stack.back();
Stack.pop_back();
Stack.push_back(p->rchild);
}
}
return 0;
}int InOrderTraverse(BinaryTree T) //中序遍历
{
BinaryTree* p;
vector<BinaryTree *> Stack;
Stack.push_back(&T);
while(!Stack.empty())
{
while((p = Stack.back()) != NULL)
Stack.push_back(p->lchild);
Stack.pop_back();
if(!Stack.empty())
{
p = Stack.back();
Stack.pop_back();
visit(p->data);
Stack.push_back(p->rchild);
}}
return 0;
}int main()
{
BinaryTree * T = NULL;
createBinaryTree(T);
PreOrderTraverse(*T);
InOrderTraverse(*T);
return 0;
}
注意理清楚弹栈的机制。