基本二叉樹程序C++

Question

所以我一直在學習所有關於二叉樹的知識，並決定編寫一個簡單的程序來向我自己證明我可以將我的知識應用到工作代碼中。我試圖用這個代碼做的事情是在一棵二叉樹中添加4個數字，並按照從最小到最大的順序輸出數字。雖然，我的代碼遇到了問題。當我運行代碼時，Visual Studio在第29行和第59行將其分開。我相信問題與遞歸函數addLeaf有關，但也許是其他內容。任何建議，解決方案，或輸入將不勝感激。！

#include "stdafx.h" 
#include <iostream> 
#include <cstdlib> 
#include <fstream> 
using namespace std; 

struct node 
{ 
    int data; 
    node* left; 
    node* right; 
}; 

node* root = NULL; 

node* createLeaf(int data) 
{ 
    node* n = new node; 
    n->data = data; 
    n->left = NULL; 
    n->right = NULL; 

    return n; 
} 
void addLeaf(int data) 
{ 
    node* curr = root; 


    //If tree is empty, create first node 
    if(root == NULL) 
    { 
     root = createLeaf(data); 

    } 

    //Left(Less than) 
    else if(data < curr->data) 
    { 
     //Check for curr->left 
     if(curr->left != NULL) 
     { 
      addLeaf(data); 
     } 
     else //Adds node to left if null 
     { 
      curr->left = createLeaf(data); 
     } 
    } 
    //Right(greater than) 
    else if(data > curr->data) 
    { 
     //Check for curr->right 
     if(curr->right != NULL) 
     { 
      addLeaf(data); 
     } 
     else //Adds node if right is Null 
     { 
      curr->right = createLeaf(data); 
     } 
    } 
    else 
    { 
     cout << "The data " << data << " has already been received\n"; 
    } 


} 

void printTree(node* Ptr) 
{ 


    if(root != NULL) 
    { 
     if(Ptr->left != NULL) 
     { 
      printTree(Ptr->left); 
     } 
     cout << Ptr->data << " "; 
     if(Ptr->right != NULL) 
     { 
      printTree(Ptr->right); 
     } 
     cout << Ptr->data << " "; 
    } 
    else 
    { 
     cout << "The Tree is empty\n"; 
    } 


} 

int main() 
{ 
    int data[4] = {1, 7, 5, 4}; 
    node* Ptr = root; 


    for(int i = 0; i < 4; i++) 
    { 
     addLeaf(data[i]); 
    } 

    printTree(Ptr); 



    system("PAUSE"); 
    return 0; 
} 

Answer 1

addleaf函數將無限運行。您只需不加任何檢查地添加到根目錄。 您將Ptr指定爲root，但後來使用new，將其分配給內存中某個根並未指向的新地址。 您必須通過Ptr才能參照addLeaf，否則將對其副本進行更改，該副本將在addLeaf終止時銷燬。 printTree打印當前節點值的兩倍（複製粘貼錯誤？）

下面是完整的代碼：

#include "stdafx.h" 
#include <iostream> 
#include <cstdlib> 
#include <fstream> 
using namespace std; 

struct node 
{ 
    int data; 
    node* left; 
    node* right; 
}; 

node* root = NULL; 

node* createLeaf(int data) 
{ 
    node* n = new node; 
    n->data = data; 
    n->left = NULL; 
    n->right = NULL; 

    return n; 
} 
void addLeaf(node* &curr, int data) 
{ 
    //If tree is empty, create first node 
    if(curr == NULL) 
    { 
     curr = createLeaf(data); 
    } 

    //Left(Less than) 
    else if(data < curr->data) 
    { 
     addLeaf (curr->left, data); 
    } 
    //Right(greater than) 
    else if(data > curr->data) 
    { 
     addLeaf(curr->right, data); 
    } 
    else 
    { 
     cout << "The data " << data << " has already been received\n"; 
    } 
} 

void printTree(node* Ptr) 
{ 


    if(root != NULL) 
    { 
     if(Ptr->left != NULL) 
     { 
     printTree(Ptr->left); 
     } 
     cout << Ptr->data << " "; 
     if(Ptr->right != NULL) 
     { 
     printTree(Ptr->right); 
     } 
    } 
    else 
    { 
     cout << "The Tree is empty\n"; 
    } 


} 

int main() 
{ 
    int data[4] = {1, 7, 5, 4}; 

    for(int i = 0; i < 4; i++) 
    { 
     addLeaf(root, data[i]); 
    } 

    printTree(root); 

    system("PAUSE"); 
    return 0; 
} 

Answer 2

一個問題，我可以發現：

void addLeaf(int data) 
{ 
    node* curr = root; 
..... 
     //Check for curr->left 
     if(curr->left != NULL) 
     { 
      addLeaf(data); 
     } 

你所謂的遞歸什麼也沒做。它只會繼續調用addLeaf函數，並且函數繼續檢查root的左邊是否爲空，並再次調用addLeaf。

重構所有的代碼。不要使用任何全局變量。確保您傳遞了正確的參數（例如，您應該將下一級節點傳遞給addLeaf）