c - C 中的二叉搜索树 SEGFAULT

Question

我正在用 C 实现 BTS。我已经实现了搜索和插入等基本功能。但我在找到最小元素和最大元素时遇到问题。这是我的代码:

#include <stdio.h>
#include <stdlib.h>

//Begin
typedef struct tree{
    int data;
    struct tree *left;
    struct tree *right;
}tree;
//----------------------------------------------------------------------------------------
tree *insert(tree *root, int data);
tree *newnode(int data);
int search(tree *root, int data);
int findMin(tree *root);
int findMax(tree *root);
//-----------------------------------------------------------------------------------------
int main(void){
    tree *root = malloc(sizeof(root));
    root->left = NULL;
    root->right = NULL;
    insert(root, 15);
    insert(root, 10);
    insert(root, 20);
    printf("%i\n", search(root ,15));
    printf("%i\n", search(root ,20));
    printf("%i\n", search(root ,10));
    printf("%i\n", search(root ,11));
    printf("%i\n", search(root ,17));   
    printf("%i\n", search(root ,10));
    printf("Min: %i\n", findMin(root));
    printf("Max: %i\n", findMax(root));
    return 0;
}
//-----------------------------------------------------------------------------------------
tree *insert(tree *root, int data){
    if(root == NULL){
        root = newnode(data);
    }

    else if(root->data < data)
            root->right = insert(root->right,data);
    else if(root->data > data)
            root->left = insert(root->left,data);
    else{
        perror("the elements already exist!");
    }
    return root;
}
//-----------------------------------------------------------------------------------------
tree *newnode(int data){
    tree *new = malloc(sizeof(tree));
    new->data = data;
    new->left = NULL;
    new->right = NULL;
    return new;
}
//-----------------------------------------------------------------------------------------
int search(tree *root, int data){
    if(root == NULL){
        return 0;
    }
    else if(root->data == data){
        return root->data;
    }
    else if (root->data < data){
        return search(root->right,data);
    }
    else if (root->data > data){
        return search(root->left,data);
    }
    else{
        perror("Error");
    }
}

//-----------------------------------------------------------------------------------------
int findMin(tree *root){
    tree *temp = root;
    while(temp != NULL){
        temp = temp->left;
    }
    return temp->data;
}
//-----------------------------------------------------------------------------------------
int findMax(tree *root){
    tree *temp = root;
    while(temp != NULL){
        temp = temp->right;
    }
    return temp->data;
}
//End 

问题出在这里: 81 返回临时->数据；

即 findmin 函数中的 while 循环

Answer 1

在测试 temp 为 null 之前，您不会返回 temp->data； (null)->data 会给你带来段错误。

尝试像这样修复循环:

int findMin(tree *root){
   tree *temp = root;
   while(temp -> left != NULL){
      temp = temp->left;
   }
   return temp->data;
}
int findMax(tree *root){
    tree *temp = root;
    while(temp->right != NULL){
        temp = temp->right;
    }
    return temp->data;
}