init

2026-02-03 23:15:17 +01:00
commit dcbd6de602
6 changed files with 329 additions and 0 deletions
@@ -0,0 +1,20 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+int *division(int input, int by)
+{
+    int value = input / by;
+    int *ptr = &value;
+    return ptr;
+}
+
+int main(void)
+{
+    int *ptr1 = division(42, 2);
+    printf("the 1st value is %d\n", *ptr1);
+    int *ptr2 = division(12, 0);
+    printf("the 2nd value is %d\n", *ptr2);
+    free(ptr1);
+    free(ptr2);
+    return EXIT_SUCCESS;
+}
@@ -0,0 +1,51 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+int **allocate_matrix(int rows, int cols)
+{
+    int **matrix = malloc(rows * sizeof(int *));
+    if (!matrix)
+        return NULL;
+    for (int i = 0; i < rows; i++)
+    {
+        matrix[i] = malloc(cols * sizeof(int));
+        if (!matrix[i])
+        {
+            for (int j = 0; j < i; j++)
+                free(matrix[j]);
+            free(matrix);
+            return NULL;
+        }
+    }
+    return matrix;
+}
+
+void free_matrix(int **matrix, int rows)
+{
+    if (!matrix)
+        return;
+    free(matrix);
+    return;
+}
+
+int main(void)
+{
+    int rows = 5;
+    int cols = 5;
+    int **matrix = allocate_matrix(rows, cols);
+    if (!matrix)
+    {
+        return EXIT_FAILURE;
+    }
+
+    for (int i = 0; i < rows; i++)
+    {
+        for (int j = 0; j < cols; j++)
+        {
+            matrix[i][j] = i * cols + j;
+        }
+    }
+
+    free_matrix(matrix, rows);
+    return EXIT_SUCCESS;
+}
@@ -0,0 +1,192 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+struct pair_list
+{
+    const char *key;
+    char *value;
+    struct pair_list *next;
+};
+
+struct hash_map
+{
+    struct pair_list **data;
+    size_t size;
+};
+
+size_t hash(const char *key)
+{
+    if (!key)
+        return 0;
+
+    uint32_t hash = 2166136261;
+    uint32_t prime = 16777619;
+
+    while (*key)
+    {
+        hash ^= *key;
+        hash *= prime;
+        key++;
+    }
+
+    return hash;
+}
+
+struct hash_map *hash_map_init(size_t size)
+{
+    struct hash_map *res = malloc(sizeof(struct hash_map));
+    if (!res)
+        return NULL;
+    res->data = calloc(size, sizeof(struct pair_list *));
+    if (!res->data)
+    {
+        free(res);
+        return NULL;
+    }
+    res->size = size;
+    return res;
+}
+
+bool hash_map_insert(struct hash_map *hash_map, const char *key, char *value,
+                     bool *updated)
+{
+    if (!hash_map || hash_map->size == 0 || !key)
+        return false;
+
+    size_t hashed_val = hash(key) % hash_map->size;
+    struct pair_list *elt = hash_map->data[hashed_val];
+    while (elt)
+    {
+        if (strcmp(key, elt->key) == 0)
+            break;
+        elt = elt->next;
+    }
+    if (!elt)
+    {
+        struct pair_list *new = calloc(1, sizeof(struct pair_list));
+        if (!new)
+            return false;
+        new->key = key;
+        new->value = value;
+        struct pair_list *res = hash_map->data[hashed_val];
+        new->next = res;
+        hash_map->data[hashed_val] = new;
+        if (updated)
+            *updated = false;
+        return true;
+    }
+    elt->value = value;
+    if (updated)
+        *updated = true;
+    return true;
+}
+
+void hash_map_free(struct hash_map *hash_map)
+{
+    if (!hash_map)
+        return;
+    for (size_t i = 0; i < hash_map->size; i++)
+    {
+        struct pair_list *elt = hash_map->data[i];
+        while (elt)
+        {
+            struct pair_list *n = elt->next;
+            free(elt);
+            elt = n;
+        }
+    }
+    free(hash_map->data);
+    free(hash_map);
+    hash_map->data = NULL;
+}
+
+void hash_map_dump(struct hash_map *hash_map)
+{
+    if (!hash_map)
+        return;
+    for (size_t i = 0; i < hash_map->size; i++)
+    {
+        struct pair_list *elt = hash_map->data[i];
+        while (elt)
+        {
+            printf("%s: %s", elt->key, elt->value);
+            elt = elt->next;
+            if (elt)
+                printf(", ");
+            else
+                putchar('\n');
+        }
+    }
+}
+
+const char *hash_map_get(const struct hash_map *hash_map, const char *key)
+{
+    if (!hash_map || hash_map->size == 0)
+        return NULL;
+    size_t hashed_val = hash(key) % hash_map->size;
+    struct pair_list *elt = hash_map->data[hashed_val];
+    while (elt)
+    {
+        if (strcmp(key, elt->key) == 0)
+            break;
+        elt = elt->next;
+    }
+    if (elt)
+        return elt->value;
+    return NULL;
+}
+
+bool hash_map_remove(struct hash_map *hash_map, const char *key)
+{
+    if (!hash_map || hash_map->size == 0)
+        return false;
+    size_t hashed_val = hash(key) % hash_map->size;
+    struct pair_list *elt = hash_map->data[hashed_val];
+    struct pair_list *prev = NULL;
+    while (elt)
+    {
+        if (strcmp(key, elt->key) == 0)
+            break;
+        prev = elt;
+        elt = elt->next;
+    }
+    if (!elt)
+        return false;
+    if (prev)
+        prev->next = elt->next;
+    else
+        hash_map->data[hashed_val] = elt->next;
+    free(elt);
+    printf("removed %s", elt->value);
+    return true;
+}
+
+int main(void)
+{
+    struct hash_map *map = hash_map_init(10);
+    if (!map)
+        return 1;
+
+    bool updated;
+    hash_map_insert(map, "key1", "value1", &updated);
+    hash_map_insert(map, "key2", "value2", &updated);
+    hash_map_insert(map, "key1", "new_value1", &updated);
+
+    hash_map_dump(map);
+
+    const char *val = hash_map_get(map, "key1");
+    if (val)
+        printf("Retrieved key1: %s\n", val);
+
+    hash_map_remove(map, "key2");
+    hash_map_dump(map);
+
+    hash_map_free(map);
+
+    printf("Everything is ok!\n");
+    return 0;
+}
@@ -0,0 +1,57 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+char shift(char c, int by)
+{
+    int start = 0;
+    if(c >= 'a' && c <= 'z')
+    {
+        start = 'a';
+    }
+    else if(c >= 'A' && c <= 'Z')
+    {
+        start = 'A';
+    }
+    else return c;
+    c -= start;
+    c += by;
+    c %= 26;
+    return c + start;
+}
+
+char *reverse_shifted(char *input, int by)
+{
+    if(!input)
+    {
+        return NULL;
+    }
+    int len = strlen(input);
+    char *res = calloc(len, sizeof(char));
+    if(!res)
+    {
+        return NULL;
+    }
+    int start = 0;
+    int end = len + 1;
+    for (int i = 0; i < len; i++)
+    {
+        char val = input[end--];
+        val = shift(val, by);
+        res[start++] = val;
+    }
+    return res;
+}
+
+int main(void)
+{
+    char *test1 = "!qxsbdc k cs csrd";
+    char *res1 = reverse_shifted(test1, 42);
+    if(!res1)
+    {
+        return EXIT_FAILURE;
+    }
+    puts(res1);
+    free(res1);
+    return EXIT_SUCCESS;
+}