My simple recursion solution in c++

  • 1

    Adding (root->left!=NULL || root->right!=NULL) judgement to improve efficiency from 6ms to 0ms

    class Solution {
        TreeNode* invertTree(TreeNode* root) {
            TreeNode* tmp;
            if(root!=NULL && (root->left!=NULL || root->right!=NULL)){//do not forget root==NULL
                tmp = root->left;
                root->left = root->right;
                root->right = tmp;
    //above three lines can be written in std::swap(root->left, root->right);
            return root;

  • 0

    Awesome. If you use markdown to present your code, it would be better.

  • 0

    @boyzhirui just change it : ) thank you>.<

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