Question

我正在尝试对树执行一些基本操作。所有功能似乎都能完美运行。仅这两个功能不能正常工作。我调用del_elements（）函数后，遍历不打印。 search（）函数显示“找不到元素！”。为什么可能会发生这种情况？

 #include<stdio.h>
    #include<stdlib.h>
    #include<malloc.h>
    struct node{
      int data;
      struct node *left;
      struct node *right;
    };
    struct node *tree=NULL;
    struct node *insert()
    {
      struct node *new_node,*ptr,*preptr;
      int n;
      printf("Enter elements in tree.\n");
      printf("Enter -1 to stop.\n");
      scanf("%d",&n);
      while(n!=-1)
      {
        new_node=(struct node *)malloc(sizeof(struct node));
        new_node->data=n;
        new_node->left=NULL;
        new_node->right=NULL;
        if(tree==NULL)
        {
          tree=new_node;
          tree->left=NULL;
          tree->right=NULL;
        }
        else
        {
          ptr=tree;
          while(ptr!=NULL)
          {
            preptr=ptr;
            if(n<ptr->data)
              ptr=ptr->left;
              else
              ptr=ptr->right;
          }
          if(n<preptr->data)
          preptr->left=new_node;
          else
          preptr->right=new_node;
        }
        scanf("%d\n",&n);
      }
      return tree;
    }
    void preorder(struct node *tree)
    {
      if(tree!=NULL)
      {
        printf("\t%d",tree->data);
        preorder(tree->left);
        preorder(tree->right);
      }
    }
    void inorder(struct node *tree)
    {
      if(tree!=NULL)
      {
        inorder(tree->left);
        printf("\t%d",tree->data);
        inorder(tree->right);
      }
    }
    void postorder(struct node *tree)
    {
      if(tree!=NULL)
      {
        postorder(tree->left);
        postorder(tree->right);
        printf("\t%d",tree->data);
      }
    }
    int search(struct node *tree,int val)  //This function is not working properly
    {  int c=0;
      if(tree==NULL)
      printf("Tree is empty");
      else if(val<tree->data)
      {
      search(tree->left,val);
      c++;
    }
      else if(val>tree->data)
      {
      search(tree->right,val);
      c++;
    }
      else
      return c;
    }
    struct node *largest(struct node *tree)
    {
      if(tree==NULL||tree->right==NULL)
      return tree;
      else
      largest(tree->right);
    }
    struct node *smallest(struct node *tree)
    {
      if(tree==NULL||tree->left==NULL)
      return tree;
      else
      smallest(tree->left);
    }
    int height(struct node *tree)
    {  int lh,rh;
      if(tree==NULL)
      return 0;
      else
      {
       lh=height(tree->left);
       rh=height(tree->right);
     if(lh>rh)
     return (lh+1);
     else
     return (rh+1);
    }
    }
    int nodes(struct node *tree)
    {
      if(tree==NULL)
      return 0;
      else
      return (nodes(tree->left)+nodes(tree->right)+1);
    }
    int internal_n(struct node *tree)
    {
      if(tree==NULL||(tree->left==NULL&&tree->right==NULL))
      return 0;
      else
      return (internal_n(tree->left)+internal_n(tree->right)+1);
    }
    int external_n(struct node *tree)
    {
      if(tree==NULL)
      return 0;
      else if(tree->left==NULL&&tree->right==NULL)
      return 1;
      else
      return (external_n(tree->left)+external_n(tree->right));
    }
    struct node *mirror(struct node *tree)
    {
      struct node *temp;
      if(tree!=NULL)
      {
        mirror(tree->left);
        mirror(tree->right);
        temp=tree->left;
        tree->left=tree->right;
        tree->right=temp;
      }
      return tree;
    }
    struct node *del(struct node *tree)
    {
      if(tree!=NULL)
      {
        del(tree->left);
        del(tree->right);
        free(tree);
      }
      return tree;
    }
    struct node *del_elements(struct node *tree,int val) //This function is not working properly.
    {
      if(tree==NULL)
      return tree;
      else if(val<tree->data)
      del_elements(tree->left,val);
      else if(val>tree->data)
      del_elements(tree->right,val);
      else
      {
        if(tree->left==NULL&&tree->right==NULL)
        {
          struct node *temp=tree;
          tree=NULL;
          free(temp);
          return tree;
        }
        else if(tree->left==NULL)
        {
          tree=tree->right;
          return tree;
        }
        else if(tree->right==NULL)
        {
          tree=tree->left;
          return tree;
        }
        else
        {
          struct node *temp=largest(tree->left);
          tree->data=temp->data;
          del_elements(tree->left,temp->data);
          return tree;
        }
      }
    }
    int main()
    {  struct node *c;
      int t=0,u,w,o;
      insert();
      printf("\nElements in PreOrder:\n");
      preorder(tree);
      printf("\nElements in InOrder:\n");
      inorder(tree);
      printf("\nElements in PostOrder:\n");
      postorder(tree);
      c=largest(tree);
      printf("\nLargest element in tree: %d",c->data);
      c=smallest(tree);
      printf("\nSmallest element in tree: %d",c->data);
     printf("\nHeight of tree: %d",height(tree));
     printf("\nTotal no. of nodes in tree: %d",nodes(tree));
     printf("\nTotal no. of internal nodes: %d",internal_n(tree));
     printf("\nTotal no. of external nodes: %d",external_n(tree));
     fflush(stdin);
     o=scanf("\nEnter element to Search: %d",&u);  
     if(o==1)
     {
     t=search(tree,u);
     if(t!=0)
     printf("\n\tElement found at %d level",t);
     else
     printf("\n\tElement not found!");
    }
    scanf("\nEnter element to be deleted: %d",&w);  
    del_elements(tree,w);
    printf("\nElements in PreOrder:\n");
    preorder(tree);
    printf("\nElements in InOrder:\n");
    inorder(tree);
    printf("\nElements in PostOrder:\n");
    postorder(tree);
     printf("\nMirror image of tree is made.");
     tree=mirror(tree);
     printf("\nElements in PreOrder:\n");
     preorder(tree);
     printf("\nElements in InOrder:\n");
     inorder(tree);
     printf("\nElements in PostOrder:\n");
     postorder(tree);
     del(tree);
     printf("\n\t\t\t\t\t\tTree deleted successfully.");
      return 0;`enter code here`
    }

Answer 1

//Wrong way to use/initialize
o=scanf("\nEnter element to Search: %d",&u) and 
scanf("\nEnter element to be deleted: %d",&w);  

//Better way to perform the operation
printf('\nEnter element to Search:'); 
scanf(" %d",&u)
o = u;`enter code here`
printf('\nEnter element to be deleted:');
scanf("%d",&w);

您不应将结果分配给变量，并且第一个参数应为格式字符串'％d'（如果是整数）。如果不起作用，请发布错误日志

del_elements（）和search（）函数无法正常工作

1 个答案: