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krahets
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@ -1149,44 +1149,47 @@ comments: true
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=== "C"
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```c title="hash_map_chaining.c"
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/* 基于数组简易实现的链式地址哈希表 */
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/* 链表节点 */
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struct node {
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Pair *pair;
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struct Node *next;
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};
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typedef struct node Node;
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/* 链式地址哈希表 */
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struct hashMapChaining {
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int size; // 键值对数量
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int capacity; // 哈希表容量
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double loadThres; // 触发扩容的负载因子阈值
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int extendRatio; // 扩容倍数
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Pair *buckets; // 桶数组
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Node **buckets; // 桶数组
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};
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typedef struct hashMapChaining hashMapChaining;
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/* 初始化桶数组 */
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hashMapChaining *newHashMapChaining() {
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// 为哈希表分配空间
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int tableSize = 4;
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/* 构造方法 */
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hashMapChaining *initHashMapChaining() {
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hashMapChaining *hashMap = (hashMapChaining *)malloc(sizeof(hashMapChaining));
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// 初始化数组
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hashMap->buckets = (Pair *)malloc(sizeof(Pair) * tableSize);
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memset(hashMap->buckets, 0, sizeof(Pair) * tableSize);
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hashMap->capacity = tableSize;
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hashMap->size = 0;
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hashMap->extendRatio = 2;
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hashMap->capacity = 4;
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hashMap->loadThres = 2.0 / 3.0;
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hashMap->extendRatio = 2;
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hashMap->buckets = (Node **)malloc(hashMap->capacity * sizeof(Node *));
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for (int i = 0; i < hashMap->capacity; i++) {
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hashMap->buckets[i] = NULL;
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}
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return hashMap;
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}
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/* 销毁哈希表 */
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void delHashMapChaining(hashMapChaining *hashMap) {
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/* 析构方法 */
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void freeHashMapChaining(hashMapChaining *hashMap) {
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for (int i = 0; i < hashMap->capacity; i++) {
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Pair *pair = &hashMap->buckets[i];
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Node *node = pair->node;
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while (node != NULL) {
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Node *temp = node;
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node = node->next;
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free(temp->val);
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Node *cur = hashMap->buckets[i];
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while (cur) {
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Node *temp = cur;
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cur = cur->next;
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free(temp->pair);
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free(temp);
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}
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}
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@ -1195,7 +1198,7 @@ comments: true
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}
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/* 哈希函数 */
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int hashFunc(hashMapChaining *hashMap, const int key) {
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int hashFunc(hashMapChaining *hashMap, int key) {
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return key % hashMap->capacity;
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}
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@ -1205,136 +1208,109 @@ comments: true
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}
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/* 查询操作 */
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char *get(hashMapChaining *hashMap, const int key) {
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char *get(hashMapChaining *hashMap, int key) {
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int index = hashFunc(hashMap, key);
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Pair *pair = &hashMap->buckets[index];
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Node *node = pair->node;
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while (node != NULL) {
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if (node->key == key) {
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return node->val;
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// 遍历桶，若找到 key 则返回对应 val
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Node *cur = hashMap->buckets[index];
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while (cur) {
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if (cur->pair->key == key) {
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return cur->pair->val;
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}
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node = node->next;
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cur = cur->next;
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}
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return NULL;
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return ""; // 若未找到 key 则返回空字符串
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}
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/* 添加操作 */
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void put(hashMapChaining *hashMap, const int key, char *val) {
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void put(hashMapChaining *hashMap, int key, const char *val) {
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// 当负载因子超过阈值时，执行扩容
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if (loadFactor(hashMap) > hashMap->loadThres) {
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extend(hashMap);
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}
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int index = hashFunc(hashMap, key);
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// 先为新节点分配空间再赋值
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// 遍历桶，若遇到指定 key ，则更新对应 val 并返回
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Node *cur = hashMap->buckets[index];
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while (cur) {
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if (cur->pair->key == key) {
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strcpy(cur->pair->val, val); // 若遇到指定 key ，则更新对应 val 并返回
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return;
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}
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cur = cur->next;
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}
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// 若无该 key ，则将键值对添加至尾部
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Pair *newPair = (Pair *)malloc(sizeof(Pair));
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newPair->key = key;
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strcpy(newPair->val, val);
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Node *newNode = (Node *)malloc(sizeof(Node));
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memset(newNode, 0, sizeof(Node));
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newNode->key = key;
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newNode->val = (char *)malloc(strlen(val) + 1);
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strcpy(newNode->val, val);
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newNode->val[strlen(val)] = '\0';
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Pair *pair = &hashMap->buckets[index];
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Node *node = pair->node;
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if (node == NULL) {
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hashMap->buckets[index].node = newNode;
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hashMap->size++;
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return;
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}
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while (node != NULL) {
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if (node->key == key) {
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// 释放先前分配的内存
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free(node->val);
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// 更新节点的值
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node->val = (char *)malloc(strlen(val) + 1);
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strcpy(node->val, val);
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node->val[strlen(val)] = '\0';
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return;
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}
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if (node->next == NULL) {
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break;
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}
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node = node->next;
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}
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node->next = newNode;
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newNode->pair = newPair;
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newNode->next = hashMap->buckets[index];
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hashMap->buckets[index] = newNode;
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hashMap->size++;
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}
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/* 删除操作 */
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void removeItem(hashMapChaining *hashMap, int key) {
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int index = hashFunc(hashMap, key);
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Pair *pair = &hashMap->buckets[index];
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Node *node = pair->node;
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// 保存后继的节点
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Node *prev = NULL;
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while (node != NULL) {
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if (node->key == key) {
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// 如果要删除的节点是桶的第一个节点
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if (prev == NULL) {
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pair->node = node->next;
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} else {
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prev->next = node->next;
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}
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// 释放内存
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free(node->val);
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free(node);
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hashMap->size--;
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return;
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}
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prev = node;
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node = node->next;
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}
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return;
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}
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/* 扩容哈希表 */
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void extend(hashMapChaining *hashMap) {
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// 暂存原哈希表
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Pair *oldBuckets = hashMap->buckets;
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int oldCapacity = hashMap->capacity;
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// 创建新的哈希表，重新分配一段空间
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Node **oldBuckets = hashMap->buckets;
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// 初始化扩容后的新哈希表
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hashMap->capacity *= hashMap->extendRatio;
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hashMap->buckets = (Pair *)malloc(sizeof(Pair) * hashMap->capacity);
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memset(hashMap->buckets, 0, sizeof(Pair) * hashMap->capacity);
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hashMap->size = 0;
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// 将原哈希表中的键值对重新哈希到新的哈希表中
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for (int i = 0; i < oldCapacity; i++) {
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Node *node = oldBuckets[i].node;
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while (node != NULL) {
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put(hashMap, node->key, node->val);
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node = node->next;
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}
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hashMap->buckets = (Node **)malloc(hashMap->capacity * sizeof(Node *));
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for (int i = 0; i < hashMap->capacity; i++) {
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hashMap->buckets[i] = NULL;
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}
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// 释放原哈希表的内存
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hashMap->size = 0;
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// 将键值对从原哈希表搬运至新哈希表
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for (int i = 0; i < oldCapacity; i++) {
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Node *node = oldBuckets[i].node;
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while (node != NULL) {
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Node *temp = node;
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node = node->next;
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free(temp->val);
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Node *cur = oldBuckets[i];
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while (cur) {
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put(hashMap, cur->pair->key, cur->pair->val);
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Node *temp = cur;
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cur = cur->next;
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// 释放内存
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free(temp->pair);
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free(temp);
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}
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}
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free(oldBuckets);
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}
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/* 删除操作 */
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void removeKey(hashMapChaining *hashMap, int key) {
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int index = hashFunc(hashMap, key);
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Node *cur = hashMap->buckets[index];
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Node *pre = NULL;
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while (cur) {
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if (cur->pair->key == key) {
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// 从中删除键值对
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if (pre) {
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pre->next = cur->next;
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} else {
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hashMap->buckets[index] = cur->next;
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}
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// 释放内存
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free(cur->pair);
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free(cur);
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hashMap->size--;
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return;
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}
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pre = cur;
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cur = cur->next;
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}
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}
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/* 打印哈希表 */
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void print(hashMapChaining *hashMap) {
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for (int i = 0; i < hashMap->capacity; i++) {
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Node *cur = hashMap->buckets[i];
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printf("[");
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Pair *pair = &hashMap->buckets[i];
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Node *node = pair->node;
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while (node != NULL) {
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if (node->val != NULL) {
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printf("%d->%s, ", node->key, node->val);
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}
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node = node->next;
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while (cur) {
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printf("%d -> %s, ", cur->pair->key, cur->pair->val);
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cur = cur->next;
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}
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printf("]\n");
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}
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return;
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}
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```
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