Assignment Week-7 : HashMap Implementation

Readme.md

@@ -1,3 +1,14 @@
-## This is the file for the Kalpavriksha Program
-
-# here i will be doing the assignments
+### Functions
+Insert (Put) – Add a key-value pair to the hash map. If the key already exists, update
+the value.
+Search (Get) – Retrieve the value associated with a given key.
+Delete (Remove) – Remove a key-value pair from the hash map.
+Display – Print all key-value pairs stored in the hash map.
+Exit – Terminate the program.
+### Constraints
+• The keys will be non-negative integers entered by the user.
+• The values will also be non-negative integers entered by the user.
+• The hash function should be modulus-based, i.e., hash(key) = key % table_size.
+• The hash table size should be fixed (choose a reasonable value, e.g., 10).
+• Collisions should be handled using separate chaining with linked lists.
+• The program should provide a simple menu-driven interface for user interaction.

implementHashmap.c

@@ -0,0 +1,219 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+typedef struct Node
+{
+    int key;
+    int value;
+    struct Node *next;
+
+} Node;
+
+typedef struct
+{
+    Node **map;
+    int size;
+
+} Hashmap;
+
+Node *createNode(int key, int value)
+{
+
+    Node *newNode = (Node *)malloc(sizeof(Node));
+    if (newNode == NULL)
+    {
+        free(newNode);
+        return NULL;
+    }
+    newNode->key = key;
+    newNode->value = value;
+    newNode->next = NULL;
+    return newNode;
+}
+
+Hashmap *createMap(int size)
+{
+
+    Hashmap *hashmap = (Hashmap *)malloc(sizeof(Hashmap));
+    if (hashmap == NULL)
+    {
+        free(hashmap);
+        return NULL;
+    }
+    hashmap->map = (Node **)malloc(sizeof(Node *) * size);
+    hashmap->size = size;
+
+    for (int idx = 0; idx < size; idx++)
+    {
+        hashmap->map[idx] = NULL;
+    }
+    return hashmap;
+}
+
+int hash(int key, int size)
+{
+    int res = key % size;
+    return res;
+}
+
+void insertIntoHashmap(Hashmap *hashmap, int key, int value)
+{
+    int idx = hash(key, hashmap->size);
+    Node *newNode = createNode(key, value);
+    if (hashmap->map[idx] == NULL)
+    {
+        hashmap->map[idx] = newNode;
+    }
+    else
+    {
+        Node *temp = hashmap->map[idx];
+        while (temp != NULL)
+        {
+
+            if (temp->key == key)
+            {
+                temp->value = value;
+                free(newNode);
+                return;
+            }
+            temp = temp->next;
+        }
+        newNode->next = hashmap->map[idx];
+        hashmap->map[idx] = newNode;
+    }
+}
+
+int search(Hashmap *hashmap, int key)
+{
+
+    int idx = hash(key, hashmap->size);
+    Node *temp = hashmap->map[idx];
+    while (temp != NULL)
+    {
+        if (temp->key == key)
+        {
+            return temp->value;
+        }
+        temp = temp->next;
+    }
+    return -1;
+}
+
+void display(Hashmap *hashmap)
+{
+
+    for (int idx = 0; idx < hashmap->size; idx++)
+    {   
+
+        Node *temp = hashmap->map[idx];
+        if(temp != NULL){
+            printf("Index:- %d ", idx + 1);
+        }
+        while (temp != NULL)
+        {
+            printf("(%d, %d) -> ", temp->key, temp->value);
+            temp = temp->next;
+            if(temp == NULL){
+                printf("NULL\n");
+            }
+        }
+
+    }
+}
+
+void delete(Hashmap *hashmap, int key)
+{
+    int idx = hash(key, hashmap->size);
+    Node *temp = hashmap->map[idx];
+    Node *prev = NULL;
+    while (temp != NULL && temp->key != key)
+    {
+        prev = temp;
+        temp = temp->next;
+    }
+    if (temp == NULL)
+    {
+        printf("Key Not Found\n");
+        return;
+    }
+    if (prev == NULL)
+    {
+        hashmap->map[idx] = temp->next;
+    }
+    else
+    {
+        prev->next = temp->next;
+    }
+    printf("Key %d Deleted!!\n", key);
+}
+
+int main()
+{
+    int mapSize = 20;
+    Hashmap *hashmap = createMap(mapSize);
+    int choice = 0;
+    int key, value;
+
+    while (1)
+    {
+        printf("Enter the Choice:- \n1. Insert\n2. Search\n3. Delete\n4. Display\n5. Exit\n>");
+        if (scanf("%d", &choice) != 1)
+        {
+            return 0;
+        }
+        switch (choice)
+        {
+        case 1:
+        {
+            printf("Enter Key: ");
+            scanf("%d", &key);
+            printf("Enter Value: ");
+            scanf("%d", &value);
+            insertIntoHashmap(hashmap, key, value);
+            break;
+        }
+
+        case 2:
+        {
+            printf("Enter Key: ");
+            scanf("%d", &key);
+            value = search(hashmap, key);
+            if (value == -1)
+            {
+                printf("Key Not Found\n");
+            }
+            else
+            {
+                printf("Value is %d.\n", value);
+            }
+            break;
+        }
+        case 3:
+        {
+
+            printf("Enter Key: ");
+            scanf("%d", &key);
+            delete (hashmap, key);
+            break;
+        }
+
+        case 4:
+        {
+            printf("HashMap:- \n");
+            display(hashmap);
+            break;
+        }
+        case 5:
+        {
+            printf("Exiting Program.\n");
+            exit(0);
+        }
+        default:
+            printf("Invalid Choice\n");
+        }
+    }
+
+    return 0;
+}