LeetCode-106-Construct Binary Tree from Inorder and Postorder Traversal

Posted 无名路人甲

tags:

篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了LeetCode-106-Construct Binary Tree from Inorder and Postorder Traversal相关的知识,希望对你有一定的参考价值。

算法描述:

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

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

For example, given

inorder = [9,3,15,20,7]
postorder = [9,15,7,20,3]

Return the following binary tree:

    3
   /   9  20
    /     15   7

解题思路:理解原理,注意细节。

    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {
        return helper(inorder, 0, inorder.size()-1, postorder, 0, postorder.size()-1);
    }
    
    TreeNode* helper(vector<int>& inorder, int is, int ie, vector<int>& postorder, int ps, int pe){
        if(is > ie || ps > pe) return nullptr;
        TreeNode* node = new TreeNode(postorder[pe]);
        int pos = 0;
        for(int i=is; i <= ie; i++){
            if(postorder[pe]==inorder[i]){
                pos = i;
                break;
            }
        }
        node -> left = helper(inorder, is, pos-1, postorder, ps, ps - (is-pos+1));
        node -> right = helper(inorder, pos+1, ie, postorder, ps - (is-pos+1)+1, pe-1);
        return node;
    }

 


以上是关于LeetCode-106-Construct Binary Tree from Inorder and Postorder Traversal的主要内容,如果未能解决你的问题,请参考以下文章

LeetCode-106-Construct Binary Tree from Inorder and Postorder Traversal

leetcode 106 Construct Binary Tree from Inorder and Postorder Traversal----- java

LeetCode106 Construct Binary Tree from Inorder and Postorder Traversal

[LeetCode] 106. Construct Binary Tree from Inorder and Postorder Traversal 由中序和后序遍历建立二叉树

LeetCode 106. Construct Binary Tree from Inorder and Postorder Traversal (用中序和后序树遍历来建立二叉树)

LeetCode106. Construct Binary Tree from Inorder and Postorder Traversal-通过中序和后续遍历还原二叉树