二叉树的遍历

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#include<iostream>#include<stack>#include<queue>using namespace std;//二叉树结点typedef struct BiTNode{//数据char data;//左右孩子指针struct BiTNode *lchild,*rchild;}BiTNode,*BiTree;//按先序序列创建二叉树int CreateBiTree(BiTree &T){char data;//按先序次序输入二叉树中结点的值（一个字符），‘#’表示空树scanf("%c",&data);if(data == '#'){T = NULL;}else{T = (BiTree)malloc(sizeof(BiTNode));//生成根结点T->data = data;//构造左子树CreateBiTree(T->lchild);//构造右子树CreateBiTree(T->rchild);}return 0;}//输出void Visit(BiTree T){if(T->data != '#'){printf("%c ",T->data);}}//先序遍历void PreOrder(BiTree T){if(T != NULL){//访问根节点Visit(T);//访问左子结点PreOrder(T->lchild);//访问右子结点PreOrder(T->rchild);}}//中序遍历  void InOrder(BiTree T){      if(T != NULL){          //访问左子结点          InOrder(T->lchild);          //访问根节点          Visit(T);          //访问右子结点          InOrder(T->rchild);      }  }  //后序遍历void PostOrder(BiTree T){if(T != NULL){//访问左子结点PostOrder(T->lchild);//访问右子结点PostOrder(T->rchild);//访问根节点Visit(T);}}/* 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 PreOrder2(BiTree T){stack<BiTree> stack;//p是遍历指针BiTree p = T;//栈不空或者p不空时循环while(p || !stack.empty()){if(p != NULL){//存入栈中stack.push(p);//访问根节点printf("%c ",p->data);//遍历左子树p = p->lchild;}else{//退栈p = stack.top();stack.pop();//访问右子树p = p->rchild;}}//while}/* 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 InOrder2(BiTree T){stack<BiTree> stack;//p是遍历指针BiTree p = T;//栈不空或者p不空时循环while(p || !stack.empty()){if(p != NULL){//存入栈中stack.push(p);//遍历左子树p = p->lchild;}else{//退栈，访问根节点p = stack.top();printf("%c ",p->data);stack.pop();//访问右子树p = p->rchild;}}//while}//后序遍历(非递归)typedef struct BiTNodePost{BiTree biTree;char tag;}BiTNodePost,*BiTreePost;void PostOrder2(BiTree T){stack<BiTreePost> stack;//p是遍历指针BiTree p = T;BiTreePost BT;//栈不空或者p不空时循环while(p != NULL || !stack.empty()){//遍历左子树while(p != NULL){BT = (BiTreePost)malloc(sizeof(BiTNodePost));BT->biTree = p;//访问过左子树BT->tag = 'L';stack.push(BT);p = p->lchild;}//左右子树访问完毕访问根节点while(!stack.empty() && (stack.top())->tag == 'R'){BT = stack.top();//退栈stack.pop();BT->biTree;printf("%c ",BT->biTree->data);}//遍历右子树if(!stack.empty()){BT = stack.top();//访问过右子树BT->tag = 'R';p = BT->biTree;p = p->rchild;}}//while}//层次遍历void LevelOrder(BiTree T){BiTree p = T;//队列queue<BiTree> queue;//根节点入队queue.push(p);//队列不空循环while(!queue.empty()){//对头元素出队p = queue.front();//访问p指向的结点printf("%c ",p->data);//退出队列queue.pop();//左子树不空，将左子树入队if(p->lchild != NULL){queue.push(p->lchild);}//右子树不空，将右子树入队if(p->rchild != NULL){queue.push(p->rchild);}}}int main(){BiTree T;CreateBiTree(T);printf("先序遍历：\n");PreOrder(T);printf("\n");printf("先序遍历(非递归)：\n");PreOrder2(T);printf("\n");printf("中序遍历：\n");InOrder(T);printf("\n");printf("中序遍历(非递归)：\n");InOrder2(T);printf("\n");printf("后序遍历：\n");PostOrder(T);printf("\n");printf("后序遍历(非递归)：\n");PostOrder2(T);printf("\n");printf("层次遍历：\n");LevelOrder(T);printf("\n");    return 0;}
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