【遍历二叉树】06二叉树曲折(Z字形)层次遍历II【Binary Tree Zigzag Level Order Traversal】

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#include <iostream>
#include <cstdio>
#include <stack>
#include <vector>
#include "BinaryTree.h"

using namespace std;


/**
 * Definition for binary tree
 * struct TreeNode {
 * int val;
 * TreeNode *left;
 * TreeNode *right;
 * TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
vector<vector<int> > zigzagLevelOrder(TreeNode *root)
{
    vector<vector<int> > matrix;
    if(root == NULL)
    {
        return matrix;
    }

    vector<int> temp;
    temp.push_back(root->val);
    matrix.push_back(temp);

    vector<TreeNode *> path;
    path.push_back(root);

    int count = 1;
    /*拨动开关-因为第二次是从右边到左边*/
    bool lefttoright = false;

    while(!path.empty())
    {
        TreeNode *tp = path.front();
        if(tp->left != NULL)
        {
            path.push_back(tp->left);
        }
        if(tp->right != NULL)
        {
            path.push_back(tp->right);
        }

        path.erase(path.begin());
        count--;

        if(count == 0 && path.size())
        {
            vector<int> tmp;
            tmp.clear();
            if(lefttoright)
            {
                /*从左到右*/
                vector<TreeNode *>::iterator it = path.begin();
                for(; it != path.end(); ++it)
                {
                    tmp.push_back( (*it)->val );
                }
                lefttoright = false;
            }
            else
            {
                /*从右到左-下面这段代码VS运行错误不知道为什么*/
                //vector<TreeNode *>::iterator it = path.end();
                //for(--it; it >= path.begin(); --it)
                //{
                //    tmp.push_back( (*it)->val );
                //}
                for (int i = path.size() - 1; i >= 0; --i)
                {
                    tmp.push_back( path[i]->val );
                }

                lefttoright = true;
            }
            matrix.push_back(tmp);
            count = path.size();
        }
    }
    return matrix;
}

// 树中结点含有分叉，
//                  8
//              /       \
//             6         1
//           /   \
//          9     2
//               / \
//              4   7
int main()
{
    TreeNode *pNodeA1 = CreateBinaryTreeNode(8);
    TreeNode *pNodeA2 = CreateBinaryTreeNode(6);
    TreeNode *pNodeA3 = CreateBinaryTreeNode(1);
    TreeNode *pNodeA4 = CreateBinaryTreeNode(9);
    TreeNode *pNodeA5 = CreateBinaryTreeNode(2);
    TreeNode *pNodeA6 = CreateBinaryTreeNode(4);
    TreeNode *pNodeA7 = CreateBinaryTreeNode(7);

    ConnectTreeNodes(pNodeA1, pNodeA2, pNodeA3);
    ConnectTreeNodes(pNodeA2, pNodeA4, pNodeA5);
    ConnectTreeNodes(pNodeA5, pNodeA6, pNodeA7);

    PrintTree(pNodeA1);

    vector<vector<int> > ans = zigzagLevelOrder(pNodeA1);

    for (int i = 0; i < ans.size(); ++i)
    {
        for (int j = 0; j < ans[i].size(); ++j)
        {
            cout << ans[i][j] << " ";
        }
        cout << endl;
    }

    DestroyTree(pNodeA1);
    return 0;
}

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#include <iostream>
#include <cstdio>
#include "BinaryTree.h"

using namespace std;

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

//创建结点
TreeNode *CreateBinaryTreeNode(int value)
{
    TreeNode *pNode = new TreeNode(value);

    return pNode;
}

//连接结点
void ConnectTreeNodes(TreeNode *pParent, TreeNode *pLeft, TreeNode *pRight)
{
    if(pParent != NULL)
    {
        pParent->left = pLeft;
        pParent->right = pRight;
    }
}

//打印节点内容以及左右子结点内容
void PrintTreeNode(TreeNode *pNode)
{
    if(pNode != NULL)
    {
        printf("value of this node is: %d\n", pNode->val);

        if(pNode->left != NULL)
            printf("value of its left child is: %d.\n", pNode->left->val);
        else
            printf("left child is null.\n");

        if(pNode->right != NULL)
            printf("value of its right child is: %d.\n", pNode->right->val);
        else
            printf("right child is null.\n");
    }
    else
    {
        printf("this node is null.\n");
    }

    printf("\n");
}

//前序遍历递归方法打印结点内容
void PrintTree(TreeNode *pRoot)
{
    PrintTreeNode(pRoot);

    if(pRoot != NULL)
    {
        if(pRoot->left != NULL)
            PrintTree(pRoot->left);

        if(pRoot->right != NULL)
            PrintTree(pRoot->right);
    }
}

void DestroyTree(TreeNode *pRoot)
{
    if(pRoot != NULL)
    {
        TreeNode *pLeft = pRoot->left;
        TreeNode *pRight = pRoot->right;

        delete pRoot;
        pRoot = NULL;

        DestroyTree(pLeft);
        DestroyTree(pRight);
    }
}