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基于栈和队列实现二叉树的遍历

JDLin 学生  2015-12-24 04:13:56

``````
/****************

*****************/
void PostOrderTraverse(NODE* pRoot) {
if (pRoot == NULL) {
return;
}
else {
PostOrderTraverse(pRoot->pLeft);
PostOrderTraverse(pRoot->pRight);
printf("%c", pRoot->chValue);
}
return;
}
``````

1.不断将左子树入栈，直到左子树为空
2.不断出栈，直到出栈元素的右子树不为空
3.如果栈不为空或当前根结点不为空，重复步骤1和2

``````
/****************

*****************/
void OrderTraverseByStack(NODE* pRoot) {
NODE* Stack[1000];
int top = 0;
while (top > 0 || pRoot != NULL) {
for (; pRoot != NULL; pRoot = pRoot->pLeft) {
Stack[top++] = pRoot;
//前序遍历
//printf("%c",pRoot->chValue);
}
for (; pRoot == NULL&&top > 0; pRoot = pRoot->pRight) {
pRoot = Stack[--top];
//中序遍历
//printf("%c", pRoot->chValue);
}
}
}
``````

1，将前序遍历代码中的left 和right 对调，并数据存在栈S中。
2，前序遍历完后，将栈S中的数据逐个出栈并打印即可。

``````
/****************

*****************/
void PostOrderTraverseByStack(NODE* pRoot) {
NODE *StackA[1000],*StackB[1000];
int topA = 0,topB = 0;
while (topA > 0 || pRoot != NULL) {
for (; pRoot != NULL;pRoot = pRoot->pRight) {
StackA[topA++] = pRoot;
StackB[topB++] = pRoot;
}
for (; pRoot == NULL&&topA > 0; pRoot = pRoot->pLeft) {
pRoot = StackA[--topA];
}
}
while (topB > 0) {
printf("%c", StackB[--topB]->chValue);
}
}
``````

``````
#include<stdio.h>
#include<stdlib.h>

#define TREELEN 6

struct NODE {
NODE* pLeft;
NODE* pRight;
char chValue;
};

void ReBuild(char* pPreOrder,char* pInOrder,int nTreeLen,NODE** pRoot) {
if (pPreOrder == NULL || pInOrder == NULL) {
return;
}
NODE* pTemp =(NODE* )malloc(sizeof(NODE));
pTemp->chValue = *pPreOrder;
pTemp->pLeft = NULL;
pTemp->pRight = NULL;
if (*pRoot == NULL) {
*pRoot = pTemp;
}
if (nTreeLen == 1) {
return;
}
char* pOrgInOrder = pInOrder;
char* pLeftEnd = pInOrder;
int nTempLen = 0;
while (*pPreOrder != *pLeftEnd) {
if (pPreOrder == NULL || pLeftEnd == NULL) {
return;
}
nTempLen++;
if (nTempLen > nTreeLen) {
break;
}
pLeftEnd++;
}
int nLeftLen = 0;
nLeftLen = (int)(pLeftEnd - pOrgInOrder);
int nRightLen = 0;
nRightLen = nTreeLen - nLeftLen - 1;
if (nLeftLen > 0) {
ReBuild(pPreOrder+1, pInOrder, nLeftLen, &((*pRoot)->pLeft));
}
if (nRightLen > 0) {
ReBuild(pPreOrder + nLeftLen + 1, pInOrder + nLeftLen +1, nRightLen, &((*pRoot)->pRight));
}
}

/****************

*****************/
void PostOrderTraverse(NODE* pRoot) {
if (pRoot == NULL) {
return;
}
else {
PostOrderTraverse(pRoot->pLeft);
PostOrderTraverse(pRoot->pRight);
printf("%c", pRoot->chValue);
}
return;
}

/****************

*****************/
void OrderTraverseByStack(NODE* pRoot) {
NODE* Stack[1000];
int top = 0;
while (top > 0 || pRoot != NULL) {
for (; pRoot != NULL; pRoot = pRoot->pLeft) {
Stack[top++] = pRoot;
//前序遍历
//printf("%c",pRoot->chValue);
}
for (; pRoot == NULL&&top > 0; pRoot = pRoot->pRight) {
pRoot = Stack[--top];
//中序遍历
printf("%c", pRoot->chValue);
}
}
}

/****************

*****************/
void PostOrderTraverseByStack(NODE* pRoot) {
NODE *StackA[1000],*StackB[1000];
int topA = 0,topB = 0;
while (topA > 0 || pRoot != NULL) {
for (; pRoot != NULL;pRoot = pRoot->pRight) {
StackA[topA++] = pRoot;
StackB[topB++] = pRoot;
}
for (; pRoot == NULL&&topA > 0; pRoot = pRoot->pLeft) {
pRoot = StackA[--topA];
}
}
while (topB > 0) {
printf("%c", StackB[--topB]->chValue);
}
}

int main() {
NODE* pRoot = NULL;
char pre[TREELEN] = { 'a','b','d','e','c','f' };
char in[TREELEN] = { 'd','b','e','a','f','c' };
ReBuild(pre, in, TREELEN, &pRoot);
printf("\n通过栈实现的中序遍历结果：\n");
OrderTraverseByStack(pRoot);
printf("\n通过递归实现的后序遍历结果：\n");
PostOrderTraverse(pRoot);
printf("\n通过栈实现的后序遍历结果：\n");
PostOrderTraverseByStack(pRoot);
getchar();
return 0;
}
``````
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7 条回复

Donald_Shallwing 2019-11-25

lm_whales 2016-05-22

xiaocongzhi 2016-04-12

``````#include <iostream>
#include <stack>
#include <queue>
#include <locale.h>
using namespace std;
typedef struct BiTNode {//二叉树结点
char data;                      //数据
struct BiTNode *lchild,*rchild; //左右孩子指针
} BiTNode,*BiTree;
int CreateBiTree(BiTree &T) {//按先序序列创建二叉树
char data;
scanf("%c",&data);//按先序次序输入二叉树中结点的值（一个字符），‘#’表示空树
if (data == '#') {
T = NULL;
} else {
T = (BiTree)malloc(sizeof(BiTNode));
T->data = data;         //生成根结点
CreateBiTree(T->lchild);//构造左子树
CreateBiTree(T->rchild);//构造右子树
}
return 0;
}
void Visit(BiTree T) {//输出
if (T->data != '#') {
printf("%c ",T->data);
}
}
void PreOrder(BiTree T) {//先序遍历
if (T != NULL) {
Visit(T);               //访问根节点
PreOrder(T->lchild);    //访问左子结点
PreOrder(T->rchild);    //访问右子结点
}
}
void InOrder(BiTree T) {//中序遍历
if (T != NULL) {
InOrder(T->lchild);     //访问左子结点
Visit(T);               //访问根节点
InOrder(T->rchild);     //访问右子结点
}
}
void PostOrder(BiTree T) {//后序遍历
if (T != NULL) {
PostOrder(T->lchild);   //访问左子结点
PostOrder(T->rchild);   //访问右子结点
Visit(T);               //访问根节点
}
}
void PreOrder2(BiTree T) {//先序遍历(非递归)
//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。
stack<BiTree> stack;
BiTree p = T;//p是遍历指针
while (p || !stack.empty()) {   //栈不空或者p不空时循环
if (p != NULL) {
stack.push(p);          //存入栈中
printf("%c ",p->data);  //访问根节点
p = p->lchild;          //遍历左子树
} else {
p = stack.top();        //退栈
stack.pop();
p = p->rchild;          //访问右子树
}
}
}
void InOrder2(BiTree T) {//中序遍历(非递归)
//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。
stack<BiTree> stack;
BiTree p = T;//p是遍历指针
while (p || !stack.empty()) {   //栈不空或者p不空时循环
if (p != NULL) {
stack.push(p);          //存入栈中
p = p->lchild;          //遍历左子树
} else {
p = stack.top();        //退栈，访问根节点
printf("%c ",p->data);
stack.pop();
p = p->rchild;          //访问右子树
}
}
}

typedef struct BiTNodePost{
BiTree biTree;
char tag;
} BiTNodePost,*BiTreePost;
void PostOrder2(BiTree T) {//后序遍历(非递归)
stack<BiTreePost> stack;
BiTree p = T;//p是遍历指针
BiTreePost BT;
while (p != NULL || !stack.empty()) {//栈不空或者p不空时循环
while (p != NULL) {//遍历左子树
BT = (BiTreePost)malloc(sizeof(BiTNodePost));
BT->biTree = p;
BT->tag = 'L';//访问过左子树
stack.push(BT);
p = p->lchild;
}
while (!stack.empty() && (stack.top())->tag == 'R') {//左右子树访问完毕访问根节点
BT = stack.top();
stack.pop();//退栈
printf("%c ",BT->biTree->data);
}
if (!stack.empty()) {//遍历右子树
BT = stack.top();
BT->tag = 'R';//访问过右子树
p = BT->biTree;
p = p->rchild;
}
}
}

void LevelOrder(BiTree T) {//层次遍历
if (T == NULL) return;
BiTree p = T;
queue<BiTree> queue;//队列
queue.push(p);//根节点入队
while (!queue.empty()) {    //队列不空循环
p = queue.front();      //对头元素出队
printf("%c ",p->data);  //访问p指向的结点
queue.pop();            //退出队列
if (p->lchild != NULL) {//左子树不空，将左子树入队
queue.push(p->lchild);
}
if (p->rchild != NULL) {//右子树不空，将右子树入队
queue.push(p->rchild);
}
}
}
int main() {
BiTree T;

setlocale(LC_ALL,"chs");
CreateBiTree(T);

printf("先序遍历        ：");PreOrder  (T);printf("\n");
printf("先序遍历(非递归)：");PreOrder2 (T);printf("\n");
printf("\n");
printf("中序遍历        ：");InOrder   (T);printf("\n");
printf("中序遍历(非递归)：");InOrder2  (T);printf("\n");
printf("\n");
printf("后序遍历        ：");PostOrder (T);printf("\n");
printf("后序遍历(非递归)：");PostOrder2(T);printf("\n");
printf("\n");
printf("层次遍历        ：");LevelOrder(T);printf("\n");

return 0;
}
//ABC##DE#G##F###
//先序遍历        ：A B C D E G F
//先序遍历(非递归)：A B C D E G F
//
//中序遍历        ：C B E G D F A
//中序遍历(非递归)：C B E G D F A
//
//后序遍历        ：C G E F D B A
//后序遍历(非递归)：C G E F D B A
//
//层次遍历        ：A B C D E F G
//

///       A
///      /
///     B
///    / \
///   C   D
///      / \
///     E   F
///      \
///       G
``````

cattpon 2016-04-10

fly_dragon_fly 2015-12-25

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