哈希桶实现

参考博客：哈希表+哈希桶简介及实现

参考的另一篇博客，将他的代码稍微改了改拿来用。

哈希桶，听名字不知道是什么，看完本质就是用链地址法来解决哈希冲突。
至于hash函数，这个作者用的应该是直接定址法。书上一般都说除留余数法用的多一点。

（编译遇到问题的，麻烦用.c后缀而不是.cpp后缀，两个语法有差别。）

#define _XOPEN_SOURCE 500

#include 
#include 
#include 


#define BUCKET_COUNT 10

typedef struct Node {
	char *key;
	char *value;
	struct Node *next;
} Node;

typedef struct hashTable {
	Node bucket[BUCKET_COUNT];
} hashTable;


void
init_hash_table (hashTable *t)
{
	if (t == NULL)
		return;
	for (int i = 0 ; i < BUCKET_COUNT; ++i) {
		t->bucket[i].key = NULL;
		t->bucket[i].next = NULL;
		t->bucket[i].value = NULL;
	}
}

int
hash (const char *key)
{
	int hash = 0;
	for (; *key != '\0'; ++key) {
		hash = hash * 33 + *key;
	}
	return hash % BUCKET_COUNT;
}

int
insert_node (hashTable *t, char *key, char *value)
{
	if (t == NULL || key == NULL || value == NULL)
		return -1;
		
	int index = hash (key);
	if (t->bucket[index].key == NULL) {//如果桶为空，则直接写入第一个桶节点
		t->bucket[index].key = strdup (key);
		t->bucket[index].value = strdup (value);
	} else {
		Node *curr, *prev;
		curr = prev = & (t->bucket[index]);
		while (curr != NULL) {
			if (strcmp (curr->key, key) == 0) {//如果key值重复，替换相应的值
				free (curr->value);
				curr->value = strdup (value);
			}
			prev = curr;
			curr = curr->next;
		}
		//没有在当前桶中找到。创建新的节点，并加入桶链表
		curr = malloc (sizeof (Node));
		*curr = (Node) {
			.key = strdup (key),
			.value = strdup (value),
			.next = NULL
		};
		prev->next = curr;
	}
	return index;
}

void
print_hash_table (hashTable *t)
{
	if (t == NULL)
		return;
	for (int i = 0; i < BUCKET_COUNT ; ++i) {
		printf ("bucket[%d]:", i);
		Node *bucket = & (t->bucket[i]);
		while (bucket != NULL) {
			printf ("%s = %s\t\t", bucket->key, bucket->value);
			bucket = bucket->next;
		}
		putchar ('\n');
	}
}

int main (int argc, char *argv[])
{
	hashTable *ht;
	ht = malloc (sizeof (hashTable));
	init_hash_table (ht);
	char *key[] = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
	               "k", "l", "m", "n", "o", "p", "q", "r", "s", "t",
	               "u", "v", "w", "x", "y", "z"
	              };
	char *value[] = {"apple", "banana", "china", "doge", "egg", "fox",
	                 "goat", "hello", "ice", "jeep", "key", "love",
	                 "mirror", "net", "orange", "panda", "quarter", "rabbit",
	                 "shark", "tea", "unix", "volley", "wolf", "x-ray", "yard", "zoo"
	                };
	for (int i = 0; i < 26; ++i) {
		insert_node (ht, key[i], value[i]);
	}
	print_hash_table (ht);
	return 0;
}