leetcode98

class Solution {
public:
    vector<int> V;
    void postTree(TreeNode* node) {
        if (node != NULL) {
            if (node->left != NULL) {
                postTree(node->left);
            }
            V.push_back(node->val);
            if (node->right != NULL) {
                postTree(node->right);
            }
        }
    }
    bool isValidBST(TreeNode* root) {
        postTree(root);
        for (int i = ; i < V.size(); i++) {
            if (V[i] <= V[i - ]) {
                return false;
            }
        }
        return true;
    }
};

补充一个python的实现：

 class Solution:
     def __init__(self):
         self.lists = []
 
     def inOrder(self,root):
         if root != None:
             if root.left != None:
                 self.inOrder(root.left)
             self.lists.append(root.val)
             if root.right != None:
                 self.inOrder(root.right)
 
     def isValidBST(self, root: 'TreeNode') -> 'bool':
         self.inOrder(root)
         n = len(self.lists)
         for i in range(n-):
             if self.lists[i] >= self.lists[i+]:
                 return False
         return True