"One Day together Leetcode" #226. Invert Binary Tree

One Day together Leetcode

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(i) Title

Source: https://leetcode.com/problems/invert-binary-tree/

Invert a binary tree.
4
/ \
2 7
/ \ / \
1 3 6 9
To
4
/ \
9 |
/ \ / \
9 6 3 1

(ii) Problem solving

The main idea: invert a binary tree. That is, the left and right node exchange locations for each node.

Problem-solving ideas: Using the pre-sequence traversal, starting from the root node, each node to the left and right node exchange position.

/** * Definition for a binary tree node. * struct TreeNode {* int val; * TreeNode *left; * TreeNode *righ T * TreeNode (int x): Val (x), left (null), right (NULL) {} *}; */classSolution { Public: treenode* inverttree (treenode* root) {dfsinverttree (root);returnRoot }//Pre-order traversal    voidPreorderinverttree (treenode* root) {if(Root==null)return;//Swap left and right nodestreenode* temp = root->left;        Root->left = root->right; Root->right = temp;if(Root->left! = NULL) Dfsinverttree (root->left);if(Root->right! = NULL) Dfsinverttree (root->right); }};

"One Day together Leetcode" #226. Invert Binary Tree