二叉树--oj1

链接: link

class Solution {
public:
    vector<int> v;
    vector<int> preorderTraversal(TreeNode* root) {
        
        if(root==nullptr)
        return v;
        v.push_back(root->val);
        preorderTraversal(root->left);
        preorderTraversal(root->right);
        return v;
        
    }
};

链接: link

#include<iostream>
#include<string>
using std::cout;
using std::endl;
using std::string;
template<class T>
struct BTNode {
    BTNode(const T& data = T())
        : _left(nullptr),
          _right(nullptr),
          _data(data) {

    }


    BTNode<T>* _left;
    BTNode<T>* _right;
    T _data;
};

template<typename T>
struct BTree {
    typedef BTNode<T> Node;
    typedef Node* pNode;
    static pNode CreatTree(string& s, int& ct) {

        if (s[ct] == '#') {
            ct++;
            return nullptr;
        }
        pNode root = new Node(s[ct++]);
        root->_left = CreatTree( s,  ct);
        root->_right = CreatTree( s,  ct);
        return root;


    }//前序创造

    static void PreOrder(pNode root) {
        if (root == NULL) {
            return;
        }

        PreOrder(root->_left);
        cout << root->_data <<" ";
        PreOrder(root->_right);
    }

};




int main() {
    string s;
    getline(std::cin, s);
    int ct = 0;
    auto a=BTree<char>::CreatTree(s, ct);
    BTree<char>::PreOrder(a);
    return 0;
}