C语言实现数据结构查找算法：折半查找、二叉排序树查找和哈希表查找

一、折半查找算法的实现

#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;
}

int main() {
    int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    int n = sizeof(arr) / sizeof(arr[0]);
    int target = 5;
    
    int result = binarySearch(arr, n, target);
    
    if (result == -1) {
        printf("Target not found\n");
    }
    else {
        printf("Target found at index %d\n", result);
    }
    
    return 0;
}

二、二叉排序树的查找算法的实现

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

struct Node {
    int data;
    struct Node* left;
    struct Node* right;
};

struct Node* createNode(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->left = NULL;
    newNode->right = NULL;
    return newNode;
}

struct Node* insert(struct Node* root, int data) {
    if (root == NULL) {
        return createNode(data);
    }
    
    if (data < root->data) {
        root->left = insert(root->left, data);
    }
    else if (data > root->data) {
        root->right = insert(root->right, data);
    }
    
    return root;
}

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

int main() {
    struct Node* root = NULL;
    int arr[] = {8, 3, 10, 1, 6, 14, 4, 7, 13};
    int n = sizeof(arr) / sizeof(arr[0]);
    int target = 6;
    
    for (int i = 0; i < n; i++) {
        root = insert(root, arr[i]);
    }
    
    struct Node* result = search(root, target);
    
    if (result == NULL) {
        printf("Target not found\n");
    }
    else {
        printf("Target found\n");
    }
    
    return 0;
}

三、哈希表查找的实现

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

#define SIZE 10

struct Person {
    char name[20];
    int age;
};

struct HashTable {
    struct Person* table[SIZE];
};

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

void insert(struct HashTable* ht, char* name, int age) {
    struct Person* newPerson = (struct Person*)malloc(sizeof(struct Person));
    strcpy(newPerson->name, name);
    newPerson->age = age;
    
    int index = hash(name);
    ht->table[index] = newPerson;
}

struct Person* search(struct HashTable* ht, char* name) {
    int index = hash(name);
    return ht->table[index];
}

int main() {
    struct HashTable ht;
    memset(&ht, 0, sizeof(ht));
    
    insert(&ht, "Alice", 20);
    insert(&ht, "Bob", 25);
    insert(&ht, "Charlie", 30);
    
    char target[] = "Bob";
    struct Person* result = search(&ht, target);
    
    if (result == NULL) {
        printf("Target not found\n");
    }
    else {
        printf("Target found: %s, %d\n", result->name, result->age);
    }
    
    return 0;
}