算法导论 12-1-3 中序遍历的非递归算法

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题目：设计一个中序遍历的非递归算法

思路：参照10-4-5节的思路，这一次换了一种写法，思路和之前的还是差不多。

#include <iostream>#include <cstdlib>#include <ctime>using namespace std;struct TreeNode{    int key;    struct TreeNode * parent;    struct TreeNode * left;    struct TreeNode * right;    TreeNode()    {        parent = NULL;        left = NULL;        right = NULL;    }};TreeNode* createTree(TreeNode * root,int d);void printTreeM(TreeNode * root);void printTreeNo(TreeNode * root);int main (){    TreeNode*root = 0;    srand(time(NULL));    int n = 13;    for (int i = 0;i < n;i ++)    {        root = createTree(root,rand());    }   // printTreeF(root);    cout <<endl;    printTreeM(root);    cout << endl;    printTreeNo(root); //   printTreeNONRECURiSION(root);}TreeNode* createTree(TreeNode * root,int d){    struct TreeNode * tmp = new struct TreeNode();    tmp->key = d;    if (NULL == root)    {        root = tmp;        return root;    }    else    {        struct TreeNode* p = NULL;        struct TreeNode* q = NULL;        p = root;        while (p != NULL)        {            q = p;            if (d < p->key )            {                p = p->left;            }            else            {                p = p->right;            }        }        if (d < q->key)        {            q->left = tmp;            tmp->parent =q;        }        else if ( d > q->key)        {            q->right = tmp;            tmp->parent =q;        }        else        {            delete tmp;        }        return root;    }}void printTreeM(TreeNode * root){    if (NULL == root)        return;    printTreeM(root->left);    cout << root->key << '\t';    printTreeM(root->right);}void printTreeNo(TreeNode * p){    TreeNode * x = NULL;    while (p != NULL)    {        if (x != p->left)        {            p = p->left;            continue;        }        cout << p->key << ' ';        if (p->right)        {            x = NULL;            p = p->right;        }        else        {            do            {                x = p;                p = p->parent;            }while(p && x == p->right);        }    }}

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