题目描述

blablabla

样例

class Solution {
public:
    bool isSymmetric(TreeNode* root) {
        stack<TreeNode*> left;
        vector<int> vval;
        auto p = root;
        while(p||left.size()){
            while(p){
                left.push(p);
                p = p->left;
            }
            auto q = left.top();
            left.pop();
            vval.push_back(q->val);
            if(q->right){
                p = q->right;
            }
        }
        int i= 0, j = vval.size()-1;
        while(i<j){
            if(vval[i]!=vval[j]) return false;
            i++;
            j--;
        }
        return true;
    }
};