从C中的字符串构建一棵树（在二叉树中定义）

Question

我在 C 中构建树时遇到问题。我尝试使用堆栈来处理嵌套括号，但我构建的树是错误的。我发现堆栈pionter有问题，太难了，我无法修复错误。

树是这样构建的：

#include <stdio.h>
#include<iostream>
#define MaxSize 30
using namespace std;
typedef char ElemType;
typedef struct Tnodes
{
    ElemType data;
    struct Tnodes* FirstChild;
    struct Tnodes* NextSibling;
} TNode;

void CreateTree(TNode*& Family, char* str)
{
    TNode* St[MaxSize], * p = NULL;
    int top = -1;
    bool k = true;      //if FirstChild or NextSibling
    Family = NULL;
    int j = 0;
    char ch = *(str + j);
    while (ch != '\0')
    {
        switch (ch)
        {
        case '(':top++; St[top] = p; k = true; break;      //if FirstChild,k=true
        case ')':top--;  break;                            
        case ',':k = false;  St[top] = p; break;               //NextSibling ,k=false                   
        default:
            p = (TNode*)malloc(sizeof(TNode));         //pcreat a new node p
            p->data = ch; p->FirstChild = p->NextSibling = NULL;

            if (Family == NULL) 
                Family = p;                          //run for the first node

            else if (k)
                St[top]->FirstChild = p;
            else if (!k)
                St[top]->NextSibling = p;
        }
        j++;
        ch = str[j];
    }
}

//print the tree
void print_family(TNode* b, int i) {
    int cnt;
    if (b) {
        for (cnt = 1; cnt < i; cnt++)
            cout << " ";
        cout << b->data << endl;
        print_family(b->FirstChild, i + 1);
        print_family(b->NextSibling, i);
    }
}
int main()
{
    char s[] = "a(b(d,e),c(g(s),f))";
    TNode* Family;
    CreateTree(Family, s);
    print_family(Family, 5);
}

Answer 1

在我的 c++ 实现中，我在这里使用了两个堆栈，尽管空间压缩仍然是 O(N)。

#include<bits/stdc++.h>
using namespace std;

struct node {
    char data;
    struct node* FirstChild;
    struct node* NextSibling;
    node(char data_) {
        data = data_;
        FirstChild = nullptr;
        NextSibling = nullptr;
    }
};

node *root = nullptr;

node *make_node(char data) {
    node *n = new node(data);
    
    if(root == nullptr) {
        root = n;
        //cout<<"rt "<<n->data<<endl;
    }
    return n;
}


void print_family(node* b, int i) {
    int cnt;
    if (b) {
        for (cnt = 1; cnt < i; cnt++)
            cout << " ";
        cout << b->data << endl;
        print_family(b->FirstChild, i + 1);
        print_family(b->NextSibling, i);
    }
}

void make_tree(string s) {

    stack<node*> st;
    stack<node*> parent;


    for(int i = 0; i < s.length(); i++) {
        if(s[i+1] == '(') {
            node *n = make_node(s[i]);
            st.push(n);
            parent.push(n);
            
        else if(s[i] == ')') {

            vector<node*> pipe;
            
            while(1) {
                if(st.top()->data == parent.top()->data){
                    break;
                }
                pipe.push_back(st.top());
                st.pop();

            }


            if(pipe.size() <= 2) {
                parent.top()->FirstChild = pipe[0];
                if(pipe.size() == 2){
                    parent.top()->FirstChild->NextSibling = pipe[1];
                }
            }

            parent.pop();
        }
        else{
            if(s[i] != ',' and s[i] != '(')
                st.push(make_node(s[i]));
        }
    }
}



int main() {
    string s = "a(b(d,e),c(g(s),f))";

    make_tree(s);


    print_family(root,5);

}

输出