leetcode 226. Invert Binary Tree(反转二叉树)

Posted by 111qqz on Wednesday, February 22, 2017

TOC

题目链接

题意:反转一棵二叉树。。。字面意思理解即可。。就是把每一棵子树的左右孩子交换。。。

思路:直接照着题意做就好了。。。没有坑。。记录的原因是听说这题比较经典(虽然毫无难度…

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    
        bool leaf(TreeNode* root)
        {
            if (root->left==NULL&&root->right==NULL) return true;
            return false;
        }
        void dfs(TreeNode* root)
        {
            if (leaf(root)) return;
            TreeNode* tmp = root->left;
            root->left = root->right;
            root->right = tmp;
            if (root->left!=NULL) dfs(root->left);
            if (root->right!=NULL) dfs(root->right);
        }
     TreeNode* invertTree(TreeNode* root) {
        if (root==NULL) return NULL;
        dfs(root);
        return root;
        
    }
};