給定一個二叉樹，檢查它是否是映象對稱的。

二話不說上來就是遞迴騷操作。

python：

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def isSymmetric(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        if root :
            return self.isEqual(root.left,root.right)
        return True
    
    def isEqual(self,l,r):
        if l != None and r != None:
            if l.val != r.val:
                return False
            else:
                return self.isEqual(l.left,r.right) & self.isEqual(l.right,r.left)
        if l == None and r == None:
            return True
        else:
            return False
            
        
 

C++： 

/**
 * 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 isSymmetric(TreeNode* root) {
        if(root) return isEqual(root->left,root->right);
        else return true;        
    }
    bool isEqual(TreeNode* l, TreeNode* r){
        if(l != NULL && r != NULL){
            if(l->val != r->val) return false;
            else return isEqual(l->right,r->left) & isEqual(l->left,r->right);
        } 
        if(l == NULL && r == NULL) return true;
        else return false;
    }
};