题解 | #对称的二叉树#

深搜

详见代码： 对称比对！

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
private:
    bool helper(TreeNode* pLeft, TreeNode* pRight){
        if(pLeft == NULL && pRight == NULL) return true;
        else if(pLeft == NULL || pRight == NULL) return false;
        return pLeft -> val == pRight -> val 
            && helper(pLeft -> left, pRight -> right)
            && helper(pLeft -> right, pRight -> left);
    }
public:
    bool isSymmetrical(TreeNode* pRoot) {
        if(pRoot == NULL) return true;
        return helper(pRoot -> left, pRoot -> right);
    }

};