"07_226" Invert Binary Tree

Invert Binary TreeTotal accepted:54994 Total submissions:130742 difficulty:easy

Invert a binary tree.

     4   /     2     7/\   /1   3 6   9

To

     4   /     7     2/\   /9   6 3   1

Trivia:
This problem is inspired by this original tweets by Max Howell:

google:90% of our engineers with the software you wrote (Homebrew), but can ' t invert a binary tree on a Whitebo ard so fuck off.

Through this problem, a good understanding of recursion.  Recursive return is what to consider clearly, you can carefully grind the problem, very good question. C language

1 /**2 * Definition for a binary tree node.3 * struct TreeNode {4 * int val;5 * struct TreeNode *left;6 * struct TreeNode *right;7  * };8  */9 structtreenode* Inverttree (structtreenode*root) {Ten     if(Root = =NULL) One         returnRoot; A     if(Root->left = = NULL && Root->right = =NULL) -         returnRoot; -     Else{ the         structtreenode* temp = root->Right ; -Root->right = root->Left ; -Root->left =temp; -     } +Root->left = Inverttree (root->Left ); -Root->right = Inverttree (root->Right ); +      A     returnRoot; at}

Here is a solution found on the Internet, written in C + +. Since this is an operation on the structure of the actual tree, it is possible to return a value without special control.

1 treenode* inverttree (treenode* root) {2     if  (root) {3         Inverttree (root-> left); 4         Inverttree (root-> right); 5         Std::swap (Root->left, root-> right); 6     }7     return  root; 8 }

"07_226" Invert Binary Tree