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open_addressing_rng_hashmap.c
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open_addressing_rng_hashmap.c
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#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <time.h>
#define DEFAULT_SIZE 3
typedef struct node
{
char *key;
size_t hash;
char *value;
} Node;
typedef struct hashmap
{
Node **array;
size_t capacity;
size_t filled;
unsigned long resizes;
unsigned long collisions;
} Hashmap;
size_t hash (char *string);
Hashmap * create ();
size_t insert (Hashmap *hm, char *key, char *val);
void resizeIfAlmostFull (Hashmap *hm);
void print (Hashmap *hm);
void clear (Hashmap **hm);
bool isPrime (unsigned long n);
unsigned long power (unsigned long a, unsigned long b, unsigned long mod);
Node * find (Hashmap *hm, char *key);
char * get (Hashmap *hm, char *key);
void delete (Hashmap *hm, char *key);
int main (void)
{
srand(time(0));
Hashmap *hm = create();
printf("\nInitial Hashmap of size %zu:\n\n", hm->capacity);
print(hm);
printf("\n--------------\n\n");
insert(hm, "dog", "woof");
insert(hm, "cat", "meow");
insert(hm, "bird", "tweet");
insert(hm, "mouse", "squeak");
insert(hm, "cow", "moo");
insert(hm, "frog", "croak");
insert(hm, "elephant", "toot");
insert(hm, "ducks", "quack");
insert(hm, "fish", "blub");
insert(hm, "seal", "ow, ow, ow");
insert(hm, "seal", "ow, ow");
print(hm);
printf("\n--------------\n\n");
delete(hm, "abc");
delete(hm, "cow");
print(hm);
insert(hm, "cow", "moo");
print(hm);
printf("%s, %s\n", get(hm, "owo"), get(hm, "uwu"));
printf("%s\n", get(hm, "abc") ? get(hm, "abc") : "Not Found");
printf("%s\n", get(hm, "seal"));
printf("R: %lu, C: %lu, Filled: %lu, Capacity: %lu\n", hm->resizes, hm->collisions, hm->filled, hm->capacity);
clear(&hm);
return 0;
}
size_t hash (char *string)
{
int num = 31;
size_t out = 0;
size_t tmp = 0;
for(size_t i = 0; string[i] != '\0'; i++)
{
tmp = string[i] + tmp*num;
out += tmp;
}
return out;
}
Hashmap *create ()
{
Hashmap *hm = malloc(sizeof(Hashmap));
hm->capacity = DEFAULT_SIZE;
hm->filled = 0;
hm->resizes = 0;
hm->collisions = 0;
hm->array = calloc(hm->capacity, sizeof(Node *));
return hm;
}
size_t insert (Hashmap *hm, char *key, char *val)
{
Node *found = find(hm,key);
if (found)
{
found->value = realloc(found->value, sizeof(char)*(strlen(val)+1));
memcpy(found->value, val, sizeof(char)*(strlen(val)+1));
return hash(key);
}
resizeIfAlmostFull(hm);
size_t hashedKey = hash(key);
Node *new = malloc(sizeof(Node));
new->key = malloc(sizeof(char) * (strlen(key) + 1));
memcpy(new->key, key, sizeof(char) * (strlen(key) + 1));
new->value = malloc(sizeof(char) * (strlen(val) + 1));
memcpy(new->value, val, sizeof(char) * (strlen(val) + 1));
new->hash = hashedKey;
size_t index = hashedKey % hm->capacity;
// need to increment through the list until a spot is found
int randInc = 0;
for (size_t i = index;; i += randInc)
{
randInc = rand() % hm->capacity;
if (hm->array[i % hm->capacity] == NULL || strcmp(hm->array[i % hm->capacity]->value, "AVAIL") == 0)
{
hm->array[i % hm->capacity] = new;
hm->filled++;
if (i != index) // collision occured
hm->collisions++;
break;
}
}
return hashedKey;
}
void resizeIfAlmostFull (Hashmap *hm)
{
if (hm->capacity * 0.7 < hm->filled)
{
size_t i;
size_t oldCap = hm->capacity;
for(i = hm->capacity * 2 + 1; !isPrime(i); i += 2) {}
hm->capacity = i;
Node **tmp = calloc(hm->capacity, sizeof(Node *));
hm->resizes++;
for (i = 0; i < oldCap; i++)
if (hm->array[i] != NULL)
tmp[i] = hm->array[i];
free(hm->array);
hm->array = tmp;
}
}
void print (Hashmap *hm)
{
Node *cur;
for(size_t i = 0; i < hm->capacity; i++)
{
cur = hm->array[i];
if (cur)
printf("K: %s V: %s\n", cur->key, cur->value);
else
printf("NULL\n");
}
}
void clear (Hashmap **hm)
{
free((*hm)->array);
free(*hm);
*hm = NULL;
}
bool isPrime (unsigned long n)
{
unsigned long a, s, d, r;
s = 0;
d = n-1;
unsigned long witnesses[] = {2, 3, 5, 7, 11};
for (a = 0; a < 5; a++)
if(witnesses[a] == n)
return true;
while (d % 2 == 0)
{
d /= 2;
s++;
}
for (a = 0; a < 5; a++)
{
if ((unsigned long)power(witnesses[a], d, n) % n == 1)
continue;
for (r = 0; r < s; r++)
if ((unsigned long)power(witnesses[a], (unsigned long)power(2, r, n)*d, n) % n == n-1)
break;
if (r == s)
return false;
}
return true;
}
unsigned long power (unsigned long a, unsigned long b, unsigned long mod)
{
if (b == 1)
return a % mod;
if (b == 0)
return 1;
if (b % 2 == 0)
return power(a*a % mod, b/2, mod);
return a * power((a*a) % mod, b/2, mod) % mod;
}
char *get (Hashmap *hm, char *key)
{
Node *found = find(hm,key);
return found ? found->value : NULL;
}
Node * find (Hashmap *hm, char *key)
{
for (size_t i = 0; i < hm->capacity;)
{
if (hm->array[i] == NULL)
++i;
else if (strcmp(hm->array[i]->key, key) == 0) // if the keys are the same, return the Node
return hm->array[i];
else
++i;
}
return NULL;
}
void delete (Hashmap *hm, char *key)
{
Node *found = find(hm, key);
Node *new = malloc(sizeof(Node *));
if (found)
{
new->value = "AVAIL";
new->key = "AVAIL";
new->hash = hash(key);
hm->array[hash(key) % hm->capacity] = new;
}
}