樹

第一種表示方法：
雙親數組表示法，第0號不存數據，從第1號開始存放。

子女—兄弟表示法

tree.h

#ifndef TREE_H
#define TREE_H

typedef char ElemType;
typedef struct TreeNode
{
    ElemType data;
    TreeNode * firstNode;
    TreeNode * nextSibling;
}TreeNode ,*Tree;

TreeNode * FindValue(TreeNode *ptr,ElemType x);
TreeNode * FindParent(TreeNode *ptr,ElemType x);
TreeNode * MakeRoot(ElemType x);
TreeNode * InsertChild(TreeNode *ptr,ElemType x);
TreeNode * InsertSib(TreeNode *ptr,ElemType x);

#endif

Tree.cpp

#include <tree.h>
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <assert.h>

TreeNode * FindValue(TreeNode *ptr,ElemType x)
{
    if(ptr == NULL || ptr->data == x)
        {
            return ptr;
        }
    else{
        TreeNode *p = ptr->firstchild;
        TreeNode *res = NULL;
        while(p != NULL && (res = FindValue(p,x)) == NULL)
        {//如果有左孩子而且左孩子的分支裏未找到
            p = p->nextSibling;
        }
        return res;
    }
}

TreeNode * FindParent(TreeNode *ptr,ElemType x)
{
    if(ptr == NULL || child== NULL || ptr==child)
    {
        return ptr;
    }else
    {
        return Parent(ptr,child);
    }
}

TreeNode * Parent(TreeNode *ptr,ElemType x)
{
    if(ptr == NULL ) return ptr;
    TreeNode *p = ptr->firstchild;
    TreeNode *tmp = p;
    while(p != NULL && p != child)
    {//如果 p 不爲空 p不等於孩子
        TreeNode *res = Parent(p,child); //在 左孩子結點找 child 的返回值
        if(res != NULL) return res; //找到了
        p = p->nextSibling;//沒找到 在兄弟結點找
    }
    if(p!=NULL) // 找到child了
    {
        return ptr;
    }else    // p==NULL
    {
        return NULL;
    }
}

TreeNode *BuyNOde()
{
    TreeNode *s = (TreeNode *)malloc(sizeof(TreeNode));
    assert(s != NULL);
    s->firstchild = NULL;
    s->nextSibling = NULL;
    return s;
}

TreeNode *MakeRoot(ElemType x)
{
    TreeNode *root = BuyNode();
    root->data = x;
    return root;
}

TreeNode * InsertChild(TreeNode *ptr,Elemtype x)
{
    if(ptr == NULL)
    {
        return ptr;
    }
    TreeNode *s = BuyNode();
    s->data = x;
    if(ptr->firstchild == NULL)
    {
        ptr->firstchild = s;
    }else
    {
        TreeNode *p = NULL;
        p=ptr->firstchild;
        while(p->nextSibling != NULL)
        {
            p=p->nextSibling;
        }
        p->nextSibling = s;
    }
    return s;
}

TreeNode * InsertSib(TreeNode *ptr,Elemtype x)
{
    if(ptr == NULL)
    {
        return ptr;
    }
    TreeNode * s = BuyNode();
    s->data = x;
    while(ptr->nextSibling != NULL)
    {
            ptr = ptr->nextSibling;
    }
    ptr->nextSibling = s;
    return s;
}

void main()
{
    Tree root = NULL;
    root = MakeRoot('A');
    TreeNode *bp = InsertChild(root,'B');
    InsertChild(bp,'E');
    InsertChild(bp,'F');
    TreeNode *cp = InsertChild(root,'C');
    TreeNode *gp=InsertChild(cp,'G');
    InsertChild(gp,'K');
    InsertChild(gp,'L');
    TreeNode *dp = InsertChild(root,'D');
    InsertChild(dp,'H');
    InsertChild(dp,'I');
    TreeNode *jp =InsertChild(dp,'J');
    InsertChild(jp,'M');

    Elemtype ar[] = {"ABCDEFGHIJKLMNOP"};
    int n = strlen(ar);
    for(int i = 0;i<n;++i)
    {
        TreeNode *p = FindValue(root,ar[i]);
        if(p!=NULL)
        {
            printf("%x==%c\n",p,p->data);
            TreeNode *pa = FindParent(root,p);
            if(pa != NULL)
            {
                printf("%c => parent:%c\n",p->data,pa->data);
            }else
            {
                printf("no parents\n");
            }
        }
        else
        {
            printf("not find value.\n");
        }
    }

}

測試結果：