二叉树

 

方法二：

 1 #include<iostream>
 2 using namespace std;
 3  
 4 struct BTNode
 5 {
 6  
 7     char data;
 8     BTNode *left, *right;
 9     BTNode(char val) : data(val), left(NULL), right(NULL) {}
10     ~BTNode()
11     {
12         delete left;
13         delete right;
14     }
15 };
16  
17 void CreateBTree(BTNode *&root)
18 {
19     char ch; //要插入的数据  
20     cin >> ch;
21     if (ch == '#')
22         root = NULL;
23     else
24     {
25         root = new BTNode(ch);
26         printf("请输入%c的左孩子：", ch);
27         CreateBTree(root->left);
28         printf("请输入%c的右孩子：", ch);
29         CreateBTree(root->right);
30     }
31 }
32  
33 int main()
34 {
35     BTNode *root;
36     return 0;
37 }

 

 1 #include<iostream>
 2 using namespace std;
 3  
 4 struct BTNode
 5 {
 6  
 7     char data;
 8     BTNode *left, *right;
 9     BTNode(char val) : data(val), left(NULL), right(NULL) {}
10     ~BTNode()
11     {
12         delete left;
13         delete right;
14     }
15 };
16  
17 void CreateBTree(BTNode *&root)
18 {
19     char ch; //要插入的数据  
20     cin >> ch;
21     if (ch == '#')
22         root = NULL;
23     else
24     {
25         root = new BTNode(ch);
26         root->data = ch;
27         printf("请输入%c的左孩子：", ch);
28         CreateBTree(root->left);
29         printf("请输入%c的右孩子：", ch);
30         CreateBTree(root->right);
31     }
32 }
33  
34 int main()
35 {
36     BTNode *root;
37     return 0;
38 }

 

struct TreeNode{
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode():val(0),left(nullptr),right(nullptr){}
    TreeNode(int x):val(x),left(nullptr),right(nullptr){}
    TreeNode(int x,TreeNode *l,TreeNode *r):val(x),left(l),right(r){}
};

TreeNode *RebuildTree(string s){
    //第一步，字符串转数组
    stringstream ss;
    ss<<s.substr(1,s.size()-2);//去除头尾的[]后输入ss
    string tmp;
    vector<TreeNode *> v_node;
    while (getline(ss,tmp,',')){
        if(tmp == "null")
            v_node.push_back(nullptr);
        else
            v_node.push_back(new TreeNode(stoi(tmp)));
    }
    
    int length = v_node.size();
    //第二步，判断数组长度是否满足完整的二叉树长度
    //部分输入会省略掉尾部的null节点，需要补足才能正常生成
    int x = 0;
    while(x<length){
        x = (x<<1)|1;
    }
    length = x;
    for(int i=length;i<x;++i)
        v_node.push_back(nullptr);
    //第三步，二叉树生成，因为节点已经在上面申请了，此处只需要指向即可
    TreeNode *root = nullptr;
    if(length)
        root = v_node[0];
    for(int i=0;i<length/2;i++){
        TreeNode *p = v_node[i];
        p->left = v_node[2*i+1];
        p->right = v_node[2*i+2];
    }
    return root;
}

 

posted @ 2018-09-12 20:52  苏格拉底的落泪  阅读(139)  评论(0)  编辑  收藏  举报