二叉树的递归与非递归遍历算法

来源：互联网发布：vr合成软件编辑：程序博客网时间：2024/05/20 21:20
/*二叉树的遍历**/ #include <iostream>#include<string.h>#include<stack> using namespace std;typedef struct node{    char data;    struct node *lchild,*rchild;}BinTree;typedef struct node1{    BinTree *btnode;    bool isFirst;}BTNode;void creatBinTree(char *s,BinTree *&root)  //创建二叉树，s为形如A(B,C(D,E))形式的字符串 {    int i;    bool isRight=false;    stack<BinTree*> s1;          //存放结点     stack<char> s2;              //存放分隔符    BinTree *p,*temp;    root->data=s[0];    root->lchild=NULL;    root->rchild=NULL;    s1.push(root);    i=1;    while(i<strlen(s))    {        if(s[i]=='(')        {            s2.push(s[i]);            isRight=false;        }            else if(s[i]==',')            {            isRight=true;        }        else if(s[i]==')')        {            s1.pop();            s2.pop();        }        else if(isalpha(s[i]))        {            p=(BinTree *)malloc(sizeof(BinTree));            p->data=s[i];            p->lchild=NULL;            p->rchild=NULL;            temp=s1.top();            if(isRight==true)                {                temp->rchild=p;                cout<<temp->data<<"的右孩子是"<<s[i]<<endl;            }            else            {                temp->lchild=p;                cout<<temp->data<<"的左孩子是"<<s[i]<<endl;            }            if(s[i+1]=='(')                s1.push(p);        }        i++;    }    }void display(BinTree *root)        //显示树形结构 {    if(root!=NULL)    {        cout<<root->data;        if(root->lchild!=NULL)        {            cout<<'(';            display(root->lchild);        }        if(root->rchild!=NULL)        {            cout<<',';            display(root->rchild);            cout<<')';        }    }}void preOrder1(BinTree *root)     //递归前序遍历 {    if(root!=NULL)    {        cout<<root->data<<" ";        preOrder1(root->lchild);        preOrder1(root->rchild);    }}void inOrder1(BinTree *root)      //递归中序遍历{    if(root!=NULL)    {        inOrder1(root->lchild);        cout<<root->data<<" ";        inOrder1(root->rchild);    }} void postOrder1(BinTree *root)    //递归后序遍历{    if(root!=NULL)    {        postOrder1(root->lchild);        postOrder1(root->rchild);        cout<<root->data<<" ";    }    } void preOrder2(BinTree *root)     //非递归前序遍历 {    stack<BinTree*> s;    BinTree *p=root;    while(p!=NULL||!s.empty())    {        while(p!=NULL)        {            cout<<p->data<<" ";            s.push(p);            p=p->lchild;        }        if(!s.empty())        {            p=s.top();            s.pop();            p=p->rchild;        }    }}void inOrder2(BinTree *root)      //非递归中序遍历{    stack<BinTree*> s;    BinTree *p=root;    while(p!=NULL||!s.empty())    {        while(p!=NULL)        {            s.push(p);            p=p->lchild;        }        if(!s.empty())        {            p=s.top();            cout<<p->data<<" ";            s.pop();            p=p->rchild;        }    }    } void postOrder2(BinTree *root)    //非递归后序遍历{    stack<BTNode*> s;    BinTree *p=root;    BTNode *temp;    while(p!=NULL||!s.empty())    {        while(p!=NULL)              //沿左子树一直往下搜索，直至出现没有左子树的结点          {            BTNode *btn=(BTNode *)malloc(sizeof(BTNode));            btn->btnode=p;            btn->isFirst=true;            s.push(btn);            p=p->lchild;        }        if(!s.empty())        {            temp=s.top();            s.pop();            if(temp->isFirst==true)     //表示是第一次出现在栈顶              {                temp->isFirst=false;                s.push(temp);                p=temp->btnode->rchild;                }            else                        //第二次出现在栈顶              {                cout<<temp->btnode->data<<" ";                p=NULL;            }        }    }    } void postOrder3(BinTree *root)     //非递归后序遍历{    stack<BinTree*> s;    BinTree *cur;                      //当前结点     BinTree *pre=NULL;                 //前一次访问的结点     s.push(root);    while(!s.empty())    {        cur=s.top();        if((cur->lchild==NULL&&cur->rchild==NULL)||           (pre!=NULL&&(pre==cur->lchild||pre==cur->rchild)))        {            cout<<cur->data<<" ";  //如果当前结点没有孩子结点或者孩子节点都已被访问过               s.pop();            pre=cur;         }        else        {            if(cur->rchild!=NULL)                s.push(cur->rchild);            if(cur->lchild!=NULL)                    s.push(cur->lchild);        }    }    }int main(int argc, char *argv[]){    char s[100];    while(scanf("%s",s)==1)    {        BinTree *root=(BinTree *)malloc(sizeof(BinTree));        creatBinTree(s,root);        display(root);        cout<<endl;        preOrder2(root);        cout<<endl;         inOrder2(root);        cout<<endl;        postOrder2(root);        cout<<endl;        postOrder3(root);        cout<<endl;    }    return 0;}
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