C++ 代码

class Codec {    
public:
    // Encodes a tree to a single string.
    vector<int> serialize(TreeNode* root) {
        vector<int> os;
        help_se(root, os);

        return os;
    }

    void help_se(TreeNode* root, vector<int>& os){
        if (root == NULL){
            return;
        }
        else{
            os.push_back(root->val);
            help_se(root->left, os);
            help_se(root->right, os);
        }
    }

    TreeNode* deserialize(vector<int> data){
        int pos = 0;
        return help_de(data, pos, INT_MIN, INT_MAX);
    }

    TreeNode* help_de(vector<int>& is, int& pos, int minValue, int maxValue){

        if (pos >= is.size() || minValue > maxValue){
            return NULL;
        }

        int value = is[pos];

        if (value < minValue || value > maxValue){
            return NULL;
        }

        pos++;

        TreeNode* node = new TreeNode(value);
        node->left = help_de(is, pos, minValue, value);
        node->right = help_de(is, pos, value, maxValue);
        return node;
    }
};

Python 代码

class Solution:

    def serialize(self, root: TreeNode) -> str:
        """Encodes a tree to a single string.
        """

        #TC: O(N)
        #SC: O(N) (worst)

        if not root:
            return ""

        data = []

        def encoder(root):
            data.append(root.val)
            if root.left:
                encoder(root.left)
            if root.right:
                encoder(root.right)    

        encoder(root)
        print(data)
        data = ','.join([str(s) for s in data])
        return data

    def deserialize(self, data: str) -> TreeNode:
        """Decodes your encoded data to tree.
        """

        if len(data) == 0:
            return None

        data = data.split(',')
        data = [int(s) for s in data]
        data.reverse()

        def decoder(Max, Min):
            if len(data) == 0:
                return None

            if not ( Min < data[-1] < Max):
                return None

            val = data[-1]
            Node = TreeNode(val)
            data.pop()

            Node.left = decoder(val, Min)
            Node.right = decoder(Max, val)

            return Node

        return decoder(sys.maxsize, -sys.maxsize)

作者：徐辰潇
链接：https://www.acwing.com/file_system/file/content/whole/index/content/476909/
来源：AcWing
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