我的二叉树插入逻辑的缺陷在哪里？

Question

我的解决方案是这样的

/*
Node is defined as 

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

*/


node * insert (node * root, int value)
{
   bool inTreeAlready = false;
   node * cur = root;
   while(cur != NULL)
   {
       if(cur->data < value)
           cur = cur->right;
       else if(cur->data > value)
           cur = cur->left;
       else
       {
           inTreeAlready = true;
           break;
       }
   }
   if(!inTreeAlready)
   {
       cur = new node; 
       cur->data = value;
       cur->left = NULL;
       cur->right = NULL;
   }   
   return root;
}

问题提示说明您应该在插入后返回树的根。

这显然是错误的，因为输出是

Wrong Answer!
Some possible errors:
1. You returned a NULL value from the function. 
2. There is a problem with your logic
3. You are printing some value from the function

这不是很具有描述性。

我已经仔细检查了我的逻辑，但不知道交易是什么。

Answer 1

您没有将新节点添加到树中。这是修改后的版本。

node * insert (node * root, int value)
{
   bool inTreeAlready = false;
   node * cur = root;
   node *parent;
   bool right;
   while(cur != NULL)
   {
       parent = cur;
       if(cur->data < value)
       {
           cur = cur->right;
           right = true;
       }
       else if(cur->data > value)
       {
           cur = cur->left;
           right = false;
       }
       else
       {
           inTreeAlready = true;
           break;
       }
   }
   if(!inTreeAlready)
   {
       cur = new node; 
       cur->data = value;
       cur->left = NULL;
       cur->right = NULL;
       if(root == NULL) root = cur;
       else if(right) parent->right = cur;
       else parent->left = cur;
   }   
   return root;
 }