#include <stdio.h>
#include <malloc.h>
#define MaxSize 100
typedef int KeyType;                    //定义关键字类型
typedef char InfoType;
typedef struct node                     //记录类型
{KeyType key;                        //关键字项InfoType data;                      //其他数据域struct node *lchild,*rchild;        //左右孩子指针
} BSTNode;
int path[MaxSize];                      //全局变量,用于存放路径
void DispBST(BSTNode *b);               //函数说明
int InsertBST(BSTNode *&p,KeyType k)    //在以*p为根节点的BST中插入一个关键字为k的节点
{if (p==NULL)                        //原树为空, 新插入的记录为根节点{p=(BSTNode *)malloc(sizeof(BSTNode));p->key=k;p->lchild=p->rchild=NULL;return 1;}else if (k==p->key)return 0;else if (k<p->key)return InsertBST(p->lchild,k);  //插入到*p的左子树中elsereturn InsertBST(p->rchild,k);  //插入到*p的右子树中
}
BSTNode *CreatBST(KeyType A[],int n)
//由数组A中的关键字建立一棵二叉排序树
{BSTNode *bt=NULL;                   //初始时bt为空树int i=0;while (i<n)InsertBST(bt,A[i++]);       //将A[i]插入二叉排序树T中return bt;                          //返回建立的二叉排序树的根指针
}//在二叉排序树中查找，记经过的节点记录在path中，返回值为最后查找节点在path中存储的下标
int SearchBST(BSTNode *bt,KeyType k,KeyType path[],int i)
{if (bt==NULL)return i;else if (k==bt->key)    //找到了节点{path[i+1]=bt->key;  //输出其路径return i+1;}else{path[i+1]=bt->key;if (k<bt->key)SearchBST(bt->lchild,k,path,i+1);  //在左子树中递归查找elseSearchBST(bt->rchild,k,path,i+1);  //在右子树中递归查找}
}//查找并显示经过的路径
void SearchResult(BSTNode *bt, int k1)
{int r, j;r = SearchBST(bt,k1,path,-1);for (j=0; j<=r; j++)printf("%3d",path[j]);printf("\n");
}void DispBST(BSTNode *bt)
//以括号表示法输出二叉排序树bt
{if (bt!=NULL){printf("%d",bt->key);if (bt->lchild!=NULL || bt->rchild!=NULL){printf("(");DispBST(bt->lchild);if (bt->rchild!=NULL) printf(",");DispBST(bt->rchild);printf(")");}}
}int main()
{BSTNode *bt;KeyType k1=65, k2=32;int a[]= {43,91,10,18,82,65,33,59,27,73},n=10;printf("创建的BST树:");bt=CreatBST(a,n);DispBST(bt);printf("\n");printf("  查找%d关键字:",k1);SearchResult(bt,k1);printf("  查找%d关键字:",k2);SearchResult(bt,k2);return 0;
}