井号法（#）创建二叉树（利用前序遍历来建树）C++实现

/**
 *作者：魏宝航
 *2020年11月26日,下午23:55
 */
#include<iostream>
#include<vector>
using namespace std;
class Node {
public:
    char ch;
    Node* left;
    Node* right;
    Node() {
        ch = '\0';
        left = NULL;
        right = NULL;
    }
    Node(char ch, Node* left, Node* right) {
        this->ch = ch;
        this->left = left;
        this->right = right;
    }
};
static int i = 0;
Node* CreateTree(vector<char> arr,Node* root) {
    if (i < arr.size()) {
        char temp = arr[i++];
        if (temp == '#') {
            return NULL;
        }
        else {
            root = new Node();
            root->ch = temp;
            root->left = CreateTree(arr, root->left);
            root->right = CreateTree(arr, root->right);
        }
    }
    return root;
}
void preOrder(Node* root) {
    if (root == NULL) {
        return;
    }
    cout << root->ch << " ";
    preOrder(root->left);
    preOrder(root->right);
}
int main() {
    int n;
    cin >> n;
    vector<char> v;
    for (int i = 0; i < n; i++) {
        char ch;
        cin >> ch;
        v.push_back(ch);
    }
    Node* root=new Node();
    root=CreateTree(v,root);
    preOrder(root); 
}