首页 > 代码库 > Construct Binary Tree from Inorder and Postorder Traversal

Construct Binary Tree from Inorder and Postorder Traversal

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.

 

C++实现代码:

#include<iostream>#include<new>#include<vector>using namespace std;//Definition for binary treestruct TreeNode{    int val;    TreeNode *left;    TreeNode *right;    TreeNode(int x) : val(x), left(NULL), right(NULL) {}};class Solution {public:    TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {        TreeNode *root=NULL;        root=build(inorder.begin(),inorder.end(),postorder.begin(),postorder.end());        return root;    }    TreeNode *build(vector<int>::iterator ibegin,vector<int>::iterator iend,vector<int>::iterator pbegin,vector<int>::iterator pend)    {        TreeNode *root=NULL;        if(pbegin==pend||ibegin==iend)            return NULL;        auto it=ibegin;        auto tmp=pend-1;        while(it!=iend)        {            if(*it==*tmp)                break;            it++;        }        root=new TreeNode(*it);        int len=it-ibegin;        root->left=build(ibegin,it,pbegin,pbegin+len);        root->right=build(it+1,iend,pbegin+len,pend-1);        return root;    }    void preorder(TreeNode *root)    {        if(root)        {            cout<<root->val<<" ";            preorder(root->left);            preorder(root->right);        }    }    void inorder(TreeNode *root)    {        if(root)        {            inorder(root->left);            cout<<root->val<<" ";            inorder(root->right);        }    }    void postorder(TreeNode *root)    {        if(root)        {            postorder(root->left);            postorder(root->right);            cout<<root->val<<" ";        }    }};int main(){    vector<int> posorder={4,5,2,6,7,3,1};    vector<int> inorder={4,2,5,1,6,3,7};    Solution s;    TreeNode *root=s.buildTree(inorder,posorder);    s.preorder(root);    cout<<endl;    s.inorder(root);    cout<<endl;    s.postorder(root);    cout<<endl;}

运行结果:

Construct Binary Tree from Inorder and Postorder Traversal