爲什麼局部變量自動改變

-3

我編寫了一個函數來刪除二叉搜索樹中的一個節點。這是我的代碼。爲什麼局部變量自動改變

#include <iostream> 
struct BSTNode 
{ 
    int data; 
    BSTNode *left; 
    BSTNode *right; 
}; 

BSTNode * GetNode(int data); 
BSTNode * FindMin(BSTNode *root); 
BSTNode * Insert(BSTNode *root, int data); 
void PreOrder(BSTNode *root); 
BSTNode * DeleteNode(BSTNode *root,int data); 

BSTNode * GetNode(int data) 
{ 
    BSTNode *newNode = new BSTNode; 
    newNode->data = data; 
    newNode->left = NULL; 
    newNode->right = NULL; 

    return newNode; 
} 

BSTNode * FindMin(BSTNode *root) 
{ 
    if(root == NULL) 
     return root; 
    while(root->left != NULL) 
     root = root->left; 
    return root; 

} 

BSTNode * Insert(BSTNode *root, int data) 
{ 
    if(root == NULL) 
    { 
     root = GetNode(data); 
     return root; 
    } 
    else if (data <= root->data) 
     root->left = Insert(root->left, data); 
    else if (data > root->data) 
     root->right = Insert(root->right, data); 
    return root; 
} 

void PreOrder(BSTNode *root) 
{ 
    if(root == NULL) 
     return; 
    std::cout << root->data << std::endl; 
    PreOrder(root->left); 
    PreOrder(root->right); 
} 

BSTNode * DeleteNode(BSTNode *root,int data) 
{ 
    if(root == NULL) 
     return root; 
    else if(data < root->data) 
     root->left = DeleteNode(root->left, data); 
    else if(data > root->data) 
     root->right = DeleteNode(root->right, data); 
    else // Found the Node 
    { 
     // case 1: No child 
     if(root->left == NULL && root->right == NULL) 
     { 
      delete root; 
      root = NULL; 
      return root; 
     } 
     // case 2: One child 
     else if(root->left == NULL) 
     { 
      BSTNode * temp = root; 
      root = root->right; 
      delete temp; 
      return root; 
     } 
     else if(root->right = NULL) 
     { 
      BSTNode * temp = root; 
      root = root->left; 
      delete temp; 
      return root; 
     } 
     else // case 3: two child 
     { 
      BSTNode * temp = FindMin(root->right); 
      root->data = temp->data; 
      root->right = DeleteNode(root->right, temp->data); 
     } 
    } 
} 


int main() 
{ 
    BSTNode *root = NULL; 
    root = Insert(root, 15); 
    root = Insert(root, 10); 
    root = Insert(root, 20); 
    root = Insert(root, 25); 
    root = Insert(root, 8); 
    root = Insert(root, 12); 
    root = DeleteNode(root, 15); 
    PreOrder(root); 

    return 0; 
}

，但我遇到一個問題，

else // case 3: two child 
     { 
      BSTNode * temp = FindMin(root->right); 
      root->data = temp->data; 
      root->right = DeleteNode(root->right, temp->data); 
     }

程序時來到else語句，根 - >右鍵成爲NULL自動

爲什麼出現這種情況？我該如何解決它？

任何想法讚賞！

來源

2017-01-19 Superxy

'else if（root-> right = NULL）'oops。 'DeleteNode'並不總是返回任何東西。打開你的編譯器警告！ – user657267

我真不小心！謝謝。 – Superxy

在你的代碼做了一些錯字錯在檢查下面的代碼

else if(root->right = NULL) 
{ 
    BSTNode * temp = root; 
    root = root->left; 
    delete temp; 
    return root; 
}

上面一行else if(root->right = NULL)應該root->right == NULL，但你寫的root->Right = NULL。

來源

2017-01-19 05:58:21 TsunamiCoder

爲什麼局部變量自動改變

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