From 180d4982c9dfdcc2f360eebf66da5536afa51272 Mon Sep 17 00:00:00 2001 From: XiaChuerwu <93534259+XiaChuerwu@users.noreply.github.com> Date: Fri, 8 Sep 2023 00:36:49 +0800 Subject: [PATCH] feat: Add C codes for chapter_hashing (#706) * feat: Add C codes for chapter_hashing * fix:Make corrections to the formatting * fix:Fixing Test Cases * fix:Fixing Test Cases * fix:revised format * Update hash_map_chaining.c --------- Co-authored-by: Yudong Jin --- codes/c/chapter_hashing/hash_map_chaining.c | 242 ++++++++++++++++++++ 1 file changed, 242 insertions(+) create mode 100644 codes/c/chapter_hashing/hash_map_chaining.c diff --git a/codes/c/chapter_hashing/hash_map_chaining.c b/codes/c/chapter_hashing/hash_map_chaining.c new file mode 100644 index 000000000..e93f0ef9b --- /dev/null +++ b/codes/c/chapter_hashing/hash_map_chaining.c @@ -0,0 +1,242 @@ +/** + * File: hash_map_chaining.c + * Created Time: 2023-08-29 + * Author: SenMing (1206575349@qq.com) + */ + +#include "../utils/common.h" + +/* 键值对 int->string */ +struct node { + int key; + char *val; + struct node *next; // 下一个元素 +}; + +typedef struct node Node; + +struct pair { + Node *node; // 键值对节点 +}; + +typedef struct pair Pair; + +/* 基于数组简易实现的链式地址哈希表 */ +struct hashMapChaining { + int size; // 键值对数量 + int capacity; // 哈希表容量 + double loadThres; // 触发扩容的负载因子阈值 + int extendRatio; // 扩容倍数 + Pair *buckets; // 桶数组 +}; + +typedef struct hashMapChaining HashMapChaining; + +// 函数声明 +void extend(HashMapChaining *hashmap); + +/* 初始化桶数组 */ +HashMapChaining *newHashMapChaining() { + // 为哈希表分配空间 + int tableSize = 4; + HashMapChaining *hashmap = (HashMapChaining *)malloc(sizeof(HashMapChaining)); + + // 初始化数组 + hashmap->buckets = (Pair *)malloc(sizeof(Pair) * tableSize); + memset(hashmap->buckets, 0, sizeof(Pair) * tableSize); + + hashmap->capacity = tableSize; + hashmap->size = 0; + hashmap->extendRatio = 2; + hashmap->loadThres = 2.0 / 3; + + return hashmap; +} + +/* 销毁哈希表 */ +void delHashMapChaining(HashMapChaining *hashmap) { + for (int i = 0; i < hashmap->capacity; i++) { + Pair *pair = &hashmap->buckets[i]; + Node *node = pair->node; + while (node != NULL) { + Node *temp = node; + node = node->next; + free(temp->val); + free(temp); + } + } + free(hashmap->buckets); + free(hashmap); +} + +/* 哈希函数 */ +int hashFunc(HashMapChaining *hashmap, const int key) { + return key % hashmap->capacity; +} + +/* 负载因子 */ +double loadFactor(HashMapChaining *hashmap) { + return (double)hashmap->size / (double)hashmap->capacity; +} + +/* 查询操作 */ +const char *get(HashMapChaining *hashmap, const int key) { + int index = hashFunc(hashmap, key); + Pair *pair = &hashmap->buckets[index]; + Node *node = pair->node; + while (node != NULL) { + if (node->key == key) { + return node->val; + } + } + return NULL; +} + +/* 添加操作 */ +void put(HashMapChaining *hashmap, const int key, char *val) { + if (loadFactor(hashmap) > hashmap->loadThres) { + extend(hashmap); + } + int index = hashFunc(hashmap, key); + + // 先为新节点分配空间再赋值 + Node *newNode = (Node *)malloc(sizeof(Node)); + memset(newNode, 0, sizeof(Node)); + newNode->key = key; + newNode->val = (char *)malloc(strlen(val) + 1); + strcpy(newNode->val, val); + newNode->val[strlen(val)] = '\0'; + + Pair *pair = &hashmap->buckets[index]; + Node *node = pair->node; + if (node == NULL) { + hashmap->buckets[index].node = newNode; + hashmap->size++; + return; + } + while (node != NULL) { + if (node->key == key) { + // 释放先前分配的内存 + free(node->val); + // 更新节点的值 + node->val = (char *)malloc(strlen(val) + 1); + strcpy(node->val, val); + node->val[strlen(val)] = '\0'; + return; + } + if (node->next == NULL) { + break; + } + node = node->next; + } + node->next = newNode; + hashmap->size++; +} + +/* 删除操作 */ +void removeItem(HashMapChaining *hashmap, int key) { + int index = hashFunc(hashmap, key); + Pair *pair = &hashmap->buckets[index]; + Node *node = pair->node; + // 保存后继的节点 + Node *prev = NULL; + while (node != NULL) { + if (node->key == key) { + // 如果要删除的节点是桶的第一个节点 + if (prev == NULL) { + pair->node = node->next; + } else { + prev->next = node->next; + } + // 释放内存 + free(node->val); + free(node); + hashmap->size--; + return; + } + prev = node; + node = node->next; + } + return; +} + +/* 扩容哈希表 */ +void extend(HashMapChaining *hashmap) { + // 暂存原哈希表 + Pair *oldBuckets = hashmap->buckets; + int oldCapacity = hashmap->capacity; + + // 创建新的哈希表，重新分配一段空间 + hashmap->capacity *= hashmap->extendRatio; + hashmap->buckets = (Pair *)malloc(sizeof(Pair) * hashmap->capacity); + memset(hashmap->buckets, 0, sizeof(Pair) * hashmap->capacity); + hashmap->size = 0; + + // 将原哈希表中的键值对重新哈希到新的哈希表中 + for (int i = 0; i < oldCapacity; i++) { + Node *node = oldBuckets[i].node; + while (node != NULL) { + put(hashmap, node->key, node->val); + node = node->next; + } + } + + // 释放原哈希表的内存 + for (int i = 0; i < oldCapacity; i++) { + Node *node = oldBuckets[i].node; + while (node != NULL) { + Node *temp = node; + node = node->next; + free(temp->val); + free(temp); + } + } + free(oldBuckets); +} + +/* 打印哈希表 */ +void print(HashMapChaining *hashmap) { + for (int i = 0; i < hashmap->capacity; i++) { + printf("["); + Pair *pair = &hashmap->buckets[i]; + Node *node = pair->node; + while (node != NULL) { + if (node->val != NULL) { + printf("%d->%s, ", node->key, node->val); + } + node = node->next; + } + printf("]\n"); + } + return; +} + +/* Driver Code */ +int main() { + /* 初始化哈希表 */ + HashMapChaining *map = newHashMapChaining(); + + /* 添加操作 */ + // 在哈希表中添加键值对 (key, value) + put(map, 12836, "小哈"); + put(map, 15937, "小啰"); + put(map, 16750, "小算"); + put(map, 13276, "小法"); + put(map, 10583, "小鸭"); + printf("\n添加完成后，哈希表为\nKey -> Value\n"); + print(map); + + /* 查询操作 */ + // 向哈希表输入键 key ，得到值 value + const char *name = get(map, 13276); + printf("\n输入学号 13276 ，查询到姓名 %s\n", name); + + /* 删除操作 */ + // 在哈希表中删除键值对 (key, value) + removeItem(map, 12836); + printf("\n删除 12836 后，哈希表为\nKey -> Value\n"); + print(map); + + delHashMapChaining(map); + return 0; +}