我试图从顺序和后顺序列表中创建一个二叉树。我有两个结构，Tree和TreeNode。我先叫Tree，然后叫TreeNode。我不断过载，无法将TreeNode转换为Tree错误。我不知道如何在我的函数中添加节点。
无法从addnode函数返回正确的结构。
用C程序创建一个二叉树。需要遵循给定的结构。首先需要调用Tree结构，而不是TreeNode。添加节点功能不起作用，因为我可以添加节点并加载值。不断获取函数重载，无法将Tree转换为TreeNode结构错误。
#include "pch.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct node
{
int data;
struct node * left;
struct node * right;
} TreeNode;
typedef struct trnode
{
TreeNode * root;
} Tree;
//Prototypes for functions.
Tree * buildTree(int * in, int * post, int size);
TreeNode * addNode(int data);
int search(int inArray[], int strt, int end, int value);
Tree * buildUtil(int inArray[], int postArray[], int inStart, int inEnd, int* pIndex);
Tree * buildUtil(int inArray[], int postArray[], int inStart, int inEnd, int* pIndex)
{
int indexvalue;
TreeNode ln;
// Base case only one node
if (inStart > inEnd)
return NULL;
/* Pick current node from Postorder traversal using
postIndex and decrement postIndex */
TreeNode * node = addNode(postArray[*pIndex]);
(*pIndex)--;
indexvalue = *pIndex;
//If this node has no children then return
if (inStart == inEnd)
**//error cannot convert from TreeNode to Tree**
return node;
// Else find the index of this node in Inorder traversal
int iIndex = search(inArray, inStart, inEnd, indexvalue);
// Using index in Inorder traversal, construct left and right
//ERROR CANNOT CONVERT from TREE to node
node-> right = buildUtil(inArray, postArray, iIndex + 1, inEnd, pIndex);
node ->left = buildUtil(inArray, postArray, inStart, iIndex - 1, pIndex);
//ERROR CANT CONVERT FROM TREENODE TO TREE
return node;
}
// buildtree functioni calls helper function buildUtil which is recursive
Tree * buildTree(int * inArray, int * postArray, int size)
{
Tree *tr;
int preindex = size - 1;
tr->root;
return buildUtil(inArray, postArray, 0, preindex, &preindex);
}
/* Function to find index of value in arr[start...end]
The function assume List items that value is postsent in in[] */
int search(int inArray[], int strt, int end, int value)
{
int i;
for (i = strt; i <= end; i++) {
if (inArray[i] == value)
break;
}
return i;
}
TreeNode addNode(int data)
{
TreeNode *node = (TreeNode*)malloc(sizeof(TreeNode));
node-> data = data;
node->left = NULL;
node->right = NULL;
// no suitable constructor exists to convert from TreeNode to node
return (node);
}
int main()
{
// values of in and post lists. I can successfully read both arrays in from my read function
// in { 4, 8, 2, 5, 1, 6, 3, 7 };
// post { 8, 4, 5, 2, 6, 7, 3, 1 };
int *in = NULL;
int *post = NULL;
int insize;
int postsize;
insize = 8;
postsize = 8;
Tree * tr = buildTree(in, post, insize);
}
最佳答案
问题代码似乎将“树”与“树节点”混合在一起。具体来说，只有一棵树，从树的根节点开始。子节点（左和/或右）连接到树的根节点。然后，递归的孙节点（左右，左右，左右，左右）直到数据用尽。
根据问题代码（包括错误处理）考虑以下代码：
/*------------------------------------------------------------------------
** Compiler setup.
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*------------------------------------------------------------------------
** Memory structures.
*/
typedef struct node
{
int data;
struct node *left;
struct node *right;
} TreeNode_t;
typedef struct Tree_s
{
TreeNode_t *root;
} Tree_t;
/*------------------------------------------------------------------------
** Function to find index of value in arr[start...end]
** The function assume List items that value is postsent in in[]
**
** Returns: EXIT_SUCCESS (0) Success
** ENOENT Search found no matching value.
*/
int Search(int *_O_index, int inArray[], int strt, int end, int value)
{
int rCode = EXIT_SUCCESS;
int index;
for(index = strt; index <= end; index++)
{
if(inArray[index] == value)
break;
}
if(index > end)
{
rCode=ENOENT;
fprintf(stderr, "NOTE: (index[%d] > end[%d])\n", index, end);
goto CLEANUP;
}
//RESULTS:
if(_O_index)
*_O_index = index;
CLEANUP:
return(rCode);
}
/*------------------------------------------------------------------------
** Returns: EXIT_SUCCESS (0) Success
** ENOMEM No memory available.
*/
int AddNode(TreeNode_t **_O_node, int data)
{
int rCode = EXIT_SUCCESS;
TreeNode_t *node = NULL;
node=malloc(sizeof(TreeNode_t));
if(!node)
{
rCode=errno;
fprintf(stderr, "ERROR: node=malloc() failed. errno: %d \"%s\" \n", errno, strerror(errno));
goto CLEANUP;
}
node->data = data;
node->left = NULL;
node->right = NULL;
//RESULTS:
if(_O_node)
{
*_O_node = node;
node = NULL;
}
CLEANUP:
if(node)
free(node);
return(rCode);
}
/*------------------------------------------------------------------------
** Returns: EXIT_SUCCESS (0) Success
** Other errno values Returned by AddNode(), Search(), BuildUtil().
*/
int BuildUtil(TreeNode_t **_O_node, int inArray[], int postArray[], int inStart, int inEnd, int* pIndex)
{
int rCode = EXIT_SUCCESS;
TreeNode_t *node = NULL;
int indexvalue;
int iIndex;
/* Base case only one node */
if(inStart > inEnd)
{
fprintf(stderr, "NOTE: (inStart[%d] > inEnd[%d])\n", inStart, inEnd);
goto RESULTS;
}
/* Pick current node from Postorder traversal using
postIndex and decrement postIndex */
rCode = AddNode(&node, postArray[*pIndex]);
if(rCode)
{
fprintf(stderr, "ERROR: AddNode() failed. errno: %d \"%s\" \n", rCode, strerror(rCode));
goto CLEANUP;
}
(*pIndex)--;
indexvalue = *pIndex;
//If this node has no children then return
if(inStart == inEnd)
{
fprintf(stderr, "NOTE: no children.\n");
goto CLEANUP;
}
// Else find the index of this node in Inorder traversal
rCode=Search(&iIndex, inArray, inStart, inEnd, indexvalue);
switch(rCode)
{
case EXIT_SUCCESS:
break;
case ENOENT:
rCode = EXIT_SUCCESS;
goto RESULTS;
default:
fprintf(stderr, "ERROR: Search(&iIndex,inArray[%p], inStart[%d], inEnd[%d], indexvalue[%d]) failed. errno: %d \"%s\" \n", inArray, inStart, inEnd, indexvalue, rCode, strerror(rCode));
goto CLEANUP;
}
// Using index in Inorder traversal, construct left and right
rCode = BuildUtil(&node->right, inArray, postArray, iIndex + 1, inEnd, pIndex);
if(rCode)
{
fprintf(stderr, "ERROR: BuildUtil(node->right, inArray[%p], postArray[%p], iIndex + 1[%d], inEnd[%d], pIndex[%d]) Failed. errno: %d \"%s\"\n", inArray, postArray, iIndex + 1, inEnd, *pIndex, rCode, strerror(rCode));
goto CLEANUP;
}
rCode = BuildUtil(&node->left, inArray, postArray, inStart, iIndex - 1, pIndex);
if(rCode)
{
fprintf(stderr, "ERROR: BuildUtil(&node->left, inArray[%p], postArray[%p], iIndex + 1[%d], inEnd[%d], pIndex[%d]) Failed. errno: %d \"%s\"\n", inArray, postArray, iIndex + 1, inEnd, *pIndex, rCode, strerror(rCode));
goto CLEANUP;
}
RESULTS:
if(_O_node)
*_O_node = node;
CLEANUP:
return(rCode);
}
/*------------------------------------------------------------------------
** BuildTree function calls helper function buildUtil which is recursive
**
** Returns: EXIT_SUCCESS (0) Success
** ENOMEM No memory available.
** Other errno values Returned by BuildUtil().
*/
int BuildTree(Tree_t **_O_tree, int *inArray, int *postArray, int size)
{
int rCode = EXIT_SUCCESS;
Tree_t *tree = NULL;
int preindex = size - 1;
tree=malloc(sizeof(Tree_t));
if(!tree)
{
rCode=errno;
fprintf(stderr, "ERROR: tree=malloc() failed. errno: %d \"%s\"\n", errno, strerror(errno));
goto CLEANUP;
}
rCode = BuildUtil(&tree->root, inArray, postArray, 0, preindex, &preindex);
if(rCode)
{
fprintf(stderr, "ERROR: tree->root = buildUtil() failed. errno: %d \"%s\"\n", rCode, strerror(rCode));
goto CLEANUP;
}
//RESULTS:
if(_O_tree)
*_O_tree = tree;
CLEANUP:
return(rCode);
}
/*------------------------------------------------------------------------
** Program start.
*/
int main()
{
int rCode = EXIT_SUCCESS;
int in[] = { 4, 8, 2, 5, 1, 6, 3, 7 };
int post[] = { 8, 4, 5, 2, 6, 7, 3, 1 };
int insize = 8;
Tree_t *tree = NULL;
rCode = BuildTree(&tree, in, post, insize);
if(rCode)
{
fprintf(stderr, "ERROR: BuildTree() failed. errno: %d \"%s\"\n", rCode, strerror(rCode));
goto CLEANUP;
}
CLEANUP:
return(rCode);
}
关于c - 创建二叉树和函数重载并转换错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/58783783/