leecode第二百二十六题（翻转二叉树）

/**
 * 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:
    void core_code(TreeNode* root) {
        TreeNode* node_temp=root->left;//交换左右子节点
        root->left=root->right;
        root->right=node_temp;
        
        if(root->left!=NULL)
            core_code(root->left);//分别对左右子节点做同一操作
        if(root->right!=NULL)
            core_code(root->right);
    }
    
    TreeNode* invertTree(TreeNode* root) {
        if(root==NULL)//首先判断边界
            return root;
        core_code(root);
        return root;
    }
};