C语言数据结构查找算法实现：折半查找、二叉排序树查找和哈希表查找

以下是用 C 语言编写的可运行代码，实现了上述功能：

一、折半查找算法

#include <stdio.h>

int binarySearch(int arr[], int n, int target) {
    int left = 0;
    int right = n - 1;
    while (left <= right) {
        int mid = (left + right) / 2;
        if (arr[mid] == target) {
            return mid;
        } else if (arr[mid] < target) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    return -1; // 没有找到目标值
}

int main() {
    int arr[] = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19};
    int n = sizeof(arr) / sizeof(arr[0]);
    int target = 11;
    int result = binarySearch(arr, n, target);
    if (result != -1) {
        printf('目标值 %d 在有序表中的索引位置为 %d\n', target, result);
    } else {
        printf('目标值 %d 不在有序表中\n', target);
    }
    return 0;
}

二、二叉排序树查找

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

typedef struct TreeNode {
    int data;
    struct TreeNode* left;
    struct TreeNode* right;
} TreeNode;

TreeNode* insert(TreeNode* root, int data) {
    if (root == NULL) {
        TreeNode* newNode = (TreeNode*)malloc(sizeof(TreeNode));
        newNode->data = data;
        newNode->left = NULL;
        newNode->right = NULL;
        return newNode;
    }
    if (data < root->data) {
        root->left = insert(root->left, data);
    } else if (data > root->data) {
        root->right = insert(root->right, data);
    }
    return root;
}

TreeNode* search(TreeNode* root, int target) {
    if (root == NULL || root->data == target) {
        return root;
    }
    if (target < root->data) {
        return search(root->left, target);
    } else {
        return search(root->right, target);
    }
}

int main() {
    int arr[] = {5, 3, 8, 2, 4, 6, 9};
    int n = sizeof(arr) / sizeof(arr[0]);
    TreeNode* root = NULL;
    for (int i = 0; i < n; i++) {
        root = insert(root, arr[i]);
    }
    int target = 6;
    TreeNode* result = search(root, target);
    if (result != NULL) {
        printf('目标值 %d 在二叉排序树中\n', target);
    } else {
        printf('目标值 %d 不在二叉排序树中\n', target);
    }
    return 0;
}

三、哈希表查找

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

#define SIZE 10

typedef struct Node {
    char name[20];
    struct Node* next;
} Node;

int hash(char* name) {
    int sum = 0;
    for (int i = 0; i < strlen(name); i++) {
        sum += name[i];
    }
    return sum % SIZE;
}

void insert(Node* hashTable[], char* name) {
    int index = hash(name);
    Node* newNode = (Node*)malloc(sizeof(Node));
    strcpy(newNode->name, name);
    newNode->next = NULL;
    if (hashTable[index] == NULL) {
        hashTable[index] = newNode;
    } else {
        Node* temp = hashTable[index];
        while (temp->next != NULL) {
            temp = temp->next;
        }
        temp->next = newNode;
    }
}

Node* search(Node* hashTable[], char* name) {
    int index = hash(name);
    Node* temp = hashTable[index];
    while (temp != NULL) {
        if (strcmp(temp->name, name) == 0) {
            return temp;
        }
        temp = temp->next;
    }
    return NULL;
}

int main() {
    Node* hashTable[SIZE];
    for (int i = 0; i < SIZE; i++) {
        hashTable[i] = NULL;
    }
    insert(hashTable, "Alice");
    insert(hashTable, "Bob");
    insert(hashTable, "Charlie");
    char target[] = "Bob";
    Node* result = search(hashTable, target);
    if (result != NULL) {
        printf('目标值 %s 在哈希表中\n', target);
    } else {
        printf('目标值 %s 不在哈希表中\n', target);
    }
    return 0;
}