Leetcode: 101. Symmetric Tree

确认树是不是对称镜像的

思路

感觉要一路Traversal到底部，并且同时对树的分支做。

程序码

class Solution {
public:
    bool isSymmetric(TreeNode* root) {
        return isMirror(root->left, root->right);
    }
    
    bool isMirror(TreeNode* nodeA, TreeNode* nodeB) {
        if (nodeA == NULL && nodeB == NULL)
            return true;
        if (nodeA == NULL || nodeB == NULL)
            return false;
        if (nodeA->val == nodeB->val)
            return isMirror(nodeA->left, nodeB->right) && isMirror(nodeA->right, nodeB->left);
        return false;
        
    }
};

参考：
https://www.geeksforgeeks.org/symmetric-tree-tree-which-is-mirror-image-of-itself/