# Week 13 - Item 2 - Routes found in a binary tree sorting tree

Posted by ExuLt4Nt on Sun, 05 Jul 2020 18:15:05 +0200

```/*
* Copyright (c) 2017, Computer College, Yantai University
* All right reserved.
*File name: BST
*Author: Yin Na
*Completion date: Dec. 7, 2017
*Version number: v1.0
*
*Problem Description: The path found in the binary tree sort tree
*Input Description: Standard Function Input
*Program Output: Create and Find Binary Trees
*/
```

Description of the problem:

Designs an algorithm that outputs the path through which a keyword is searched when it is searched in a binary sort.

The algorithm designed for this project is reflected in the function int SearchBST(...) and void SearchResult().

```#include <stdio.h>
#include <malloc.h>
#define MaxSize 100
typedef int KeyType;                    //Define keyword type
typedef char InfoType;
typedef struct node                     //Record type
{
KeyType key;                        //Key Items
InfoType data;                      //Other data fields
struct node *lchild,*rchild;        //Left and right child pointer
} BSTNode;
int path[MaxSize];                      //Global variable to hold path
void DispBST(BSTNode *b);               //Function Description
int InsertBST(BSTNode *&p,KeyType k)    //Insert a node with the key k into the BST with *p as the root node
{
if (p==NULL)                        //The original tree is empty and the newly inserted record is the root node
{
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);  //Insert into the left subtree of *p
else
return InsertBST(p->rchild,k);  //Insert into the right subtree of *p
}
BSTNode *CreatBST(KeyType A[],int n)
//Build a binary sorting tree from keywords in array A
{
BSTNode *bt=NULL;                   //Initially bt is an empty tree
int i=0;
while (i<n)
InsertBST(bt,A[i++]);       //Insert A[i] into Binary Sort Tree T
return bt;                          //Returns the root pointer of the established binary sort tree
}

//Find in the binary sort tree, record the passed nodes in the path, return the value to find the subscript of the node stored in the path
int SearchBST(BSTNode *bt,KeyType k,KeyType path[],int i)
{
if (bt==NULL)
return i;
else if (k==bt->key)    //Node found
{
path[i+1]=bt->key;  //Output its path
return i+1;
}
else
{
path[i+1]=bt->key;
if (k<bt->key)
SearchBST(bt->lchild,k,path,i+1);  //Recursive search in left subtree
else
SearchBST(bt->rchild,k,path,i+1);  //Recursive Find in Right Subtree
}
}

//Find and display routes
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)
//Output binary sort tree bt in parentheses
{
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("Created BST tree:");
bt=CreatBST(a,n);
DispBST(bt);
printf("\n");
printf("  lookup%d Keyword:",k1);
SearchResult(bt,k1);
printf("  lookup%d Keyword:",k2);
SearchResult(bt,k2);
return 0;
}
```
Run Results 