我只是想在二叉搜索树中搜索密钥。 这就是我所做的。
int searchBST(int key,node *root){
if(root->data == key){
printf("The key %d is in the tree.\n",key);
return 1;
}
if(root->left != NULL){
searchBST(key,root->left);
return 0;
}
if(root->right != NULL){
searchBST(key,root->right);
return 0;
}
}
在main函数中，检查函数是否返回1，如果是，则键在树中。
printf("Please enter the key value you wish to search for: ");
scanf("%d",&key);
if((searchBST(key,root)) != 1)
printf("The key %d is not in the tree.\n",key);
如果密钥不在树中，则会打印：
The key %d is not in the tree.
这是正确的。所以这里有一个奇怪的部分，如果密钥在树中，有时系统会打印出来：
The key %d is in the tree.
和其他时间系统将同时打印：
The key %d is in the tree.
The key %d is not in the tree.
那么我该怎么做才能解决它？
这是我的整个代码
#include<stdio.h>
#include<malloc.h>
// This program will create a binary search tree or a max-heap, as chosen from a menu.
typedef struct BSTNode{
int data;
struct Node *left;
struct Node *right;
}node;
node* getNewNode(int data){
node *new = (node*)malloc(sizeof(node));
new->data = data;
new->left = new->right = NULL;
return new;
}
void heapPreOrder(int heapRootIndex,int array[],int numOfNodes){
int i = heapRootIndex;
printf("%d\t",array[i]);
if( 2*i+1<numOfNodes)
heapPreOrder(2*i+1,array,numOfNodes);
if(2*i+2<numOfNodes)
heapPreOrder(2*i+2,array,numOfNodes);
}
void disLevelOrder(int array[],int numOfNodes){
int i;
for(i = 0;i < numOfNodes;i++){
printf("%d\t",array[i]);
}
printf("\n");
}
node* insertBST(int data,node *root){
if(root == NULL){
root = getNewNode(data);
}
else{
if(data <= root->data){
root->left = insertBST(data,root->left);
}
else if(data >= root->data)
root->right= insertBST(data,root->right);
}
return root;
}
int searchBST(int key,node *root){
if (!root) return 0;
if (root->data == key) return 1;
if (root->data > key) return searchBST(root->left, key);
return searchBST(root->right, key);
}
void levelOrder(node* root, int level){
if (root == NULL)
return;
if (level == 1)
printf("%d\t", root->data);
else if (level > 1)
{
levelOrder(root->left, level-1);
levelOrder(root->right, level-1);
}
}
int findHeight(node* root)
{
if (root==NULL)
return 0;
else
{
int leftHeight = findHeight(root->left);
int rightHeight = findHeight(root->right);
if(leftHeight >= rightHeight)
return leftHeight+1;
else
return rightHeight+1;
}
}
void insertHeap(int key,int numOfNodes,int array[]){
int i,j;
i = numOfNodes-1;
if(i%2 == 1 && array[i] > array[(i-1)/2]){ //if left child is greater than parent
swap(&array[i],&array[(i-1)/2]);
for(j = (i-1)/2;j > 0,array[j]>array[(j- 1)/2]; j = (j- 1)/2){
swap(&array[j],&array[(j-1)/2]);
}
}
if(i%2 == 0 && array[i] > array[(i-2)/2]){//if right child is greater than parent
swap(&array[i],&array[(i-2)/2]);
for(j = (i-1)/2;j > 0,array[j]>array[(j- 1)/2]; j = (j- 1)/2){
swap(&array[j],&array[(j-1)/2]);
}
}
}
void searchHeap(int key,int array[],int numOfNodes){
int i;
for(i = 0;i < numOfNodes;i++){
if(key == array[i]){
printf("The key %d is in the heap.\n",key);
return;
}
}
printf("The key %d is not in the heap.\n",key);
}
void preorder(node *root){
if(root!=NULL){
printf("%d\t",root->data);
preorder(root->left);
preorder(root->right);
}
}
void swap(int *a,int *b){
int temp;
temp = *a;
*a = *b;
*b = temp;
}
int main(){
int i,j,numOfNodes,key,height;
char choice,option;
node *root = (node*)malloc(sizeof(node)); //initialize root;
root = NULL;
printf("Enter the number of nodes in the linked list to be initially created: ");
scanf("%d",&numOfNodes);
int array[numOfNodes]; //store all the data in the array first
printf("Enter the data value to be placed in the node: ");
scanf("%d",&array[0]);
root = insertBST(array[0],root); //create the root
//root->left = getNewNode(array[0]);
for(i = 1;i < numOfNodes;i++){
printf("Enter the data value to be placed in the node: "); //put each data into array, leave the index 0 empty
scanf("%d",&array[i]);
}
printf("What do you wish to create a Binary search Tree (B) or a Max-Heap (H)?: ");
scanf(" %c",&choice);
if(choice == 'B' || choice == 'b'){ //if user wants to build a Binary search Tree
for(i = 1;i<numOfNodes;i++){
insertBST(array[i],root);
}
printf("Binary search tree build successfully.\n");
}
if(choice == 'H'|| choice == 'h'){ //if user wants to build a Max-Heap
for(i = 1;i<numOfNodes;i++){ //build the max heap
if(i%2 == 1 && array[i] > array[(i-1)/2]){ //if left child is greater than parent
swap(&array[i],&array[(i-1)/2]);
for(j = (i-1)/2;j > 0,array[j]>array[(j- 1)/2]; j = (j- 1)/2){
swap(&array[j],&array[(j-1)/2]);
}
}
if(i%2 == 0 && array[i] > array[(i-2)/2]){ //if right child is greater than parent
swap(&array[i],&array[(i-2)/2]);
for(j = (i-1)/2;j > 0,array[j]>array[(j- 1)/2]; j = (j- 1)/2){
swap(&array[j],&array[(j-1)/2]);
}
}
}
printf("Heap successfully created.\n");
}
while(choice == 'B'||choice == 'b'){
printf("What do you wish to do?\n");
printf("Show Preorder Traversal(P)\tShow Level order Traversal(L)\tSearch(S)\tInsert(I)\tQuit(Q)\n");
printf("Please enter a choice: ");
scanf(" %c",&option);
if(option == 'p'||option == 'P'){
preorder(root);
printf("\n");
}
if(option == 'L'||option == 'l'){
height = findHeight(root);
for(i = 1;i <= height;i++){
levelOrder(root,i);
}
printf("\n");
}
if(option == 'S'||option == 's'){ //This is the part I have trouble with
printf("Please enter the key value you wish to search for: ");
scanf("%d",&key);
if((searchBST(key,root)) != 1)
printf("The key %d is not in the tree.\n",key);
}
if(option == 'I'||option == 'i'){ //if user wants to insert a number
printf("please enter the key value you wish to insert: ");
scanf("%d",&key);
insertBST(key,root);
printf("The key value %d was successfully inserted.\n",key);
}
if(option == 'q'||option == 'Q'){
printf("Thanks for using my program, please rate 100 as feedback! Have a wonderful day :)");
return 0;
}
printf("\n");
}
while(choice == 'H'|| choice == 'h'){
printf("What do you wish to do?\n");
printf("Show Preorder Traversal(P)\tShow Level order Traversal(L)\tSearch(S)\tInsert(I)\tQuit(Q)\n");
printf("Please enter a choice: ");
scanf(" %c",&option);
if(option == 'p'||option == 'P'){
heapPreOrder(0,array,numOfNodes);
printf("\n");
}
if(option == 'L'||option == 'l'){
disLevelOrder(array,numOfNodes);
printf("\n");
}
if(option == 'S'||option == 's'){
printf("Please enter the key value you wish to search for: ");
scanf("%d",&key);
searchHeap(key,array,numOfNodes);
}
if(option == 'I'||option == 'i'){ //if user wants to insert a number
printf("please enter the key value you wish to insert: ");
scanf("%d",&key);
numOfNodes++;
array[numOfNodes-1] = key;
insertHeap(key,numOfNodes,array);
printf("The key value %d was successfully inserted.\n",key);
}
if(option == 'q'||option == 'Q'){
printf("Thanks for using my program, please rate 100 as feedback! Have a wonderful day :)");
return 0;
}
printf("\n");
}
}
答案 0 :(得分：0)
您不应在整个二叉搜索树中搜索密钥。您应该遵循正确的路径。这就是为什么你应该将你的密钥与当前的根值进行比较。如果该值与key相同，则这是输出。如果密钥小于根值，则应该转到左子树，否则右转。
int searchBST(int key, node* root) {
if (!root) return 0;
if(root->data == key) {
printf("The key %d is in the tree.\n",key);
return 1;
}
if (root->data > key) return searchBST(key, root->left);
return searchBST(key, root->right);
}
在您的情况下，即使您找到了密钥，也会遍历整棵树。这就是为什么有时你得到两个输出。
答案 1 :(得分：0)
试试这个：
int searchBST(int key,node *root){
if (!root){
return 0;
}
if(root->data == key){
printf("The key %d is in the tree.\n",key);
return 1;
}
if(root->left != NULL){
return searchBST(key,root->left);
//return 0;
}
if(root->right != NULL){
return searchBST(key,root->right);
//return 0;
}
}
答案 2 :(得分：0)
编辑答案 - ：
只需像这样更改您的代码，
int searchBST(int key,node *root){
int bRet = 1; /// 1 means error
if(root->data == key){
printf("The key %d is in the tree.\n",key);
bRet = 0; /// 0 means success
return bRet;
}
if(root->left != NULL){
bRet = searchBST(key,root->left);
if(!bRet)
{
return bRet;
}
}
if(root->right != NULL){
bRet = searchBST(key,root->right);
if(!bRet)
{
return bRet;
}
}
return bRet;
}
主要功能，
printf("Please enter the key value you wish to search for: ");
scanf("%d",&key);
if(0 != searchBST(key,root))
printf("The key %d is not in the tree.\n",key);
返回值0表示成功，任何其他值（包括1表示未找到错误/密钥。
我发现了一些小问题，但我认为这些问题应该在编译时发现，比如，