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This method employs an array of linked lists (chaining) to handle collisions. Each index represents a hash code, and if multiple keys hash to the same index, we store them in a linked list at that index. This helps us efficiently manage key collisions.
Time Complexity: For each operation (put, get, remove), it is O(n) in the worst case, where n is the number of keys stored at a particular index.
Space Complexity: O(N) where N is the number of distinct keys inserted into the hash map.
1#include<stdio.h>
2#include<stdlib.h>
3
4#define MAX_SIZE 1000
5
6typedef struct Node {
7    int key, value;
8    struct Node* next;
9} Node;
10
11Node* hashMap[MAX_SIZE];
12
13unsigned int hashFunction(int key) {
14    return key % MAX_SIZE;
15}
16
17Node* createNode(int key, int value) {
18    Node* newNode = (Node*)malloc(sizeof(Node));
19    newNode->key = key;
20    newNode->value = value;
21    newNode->next = NULL;
22    return newNode;
23}
24
25void myHashMapPut(int key, int value) {
26    int hash = hashFunction(key);
27    Node* current = hashMap[hash];
28    while (current != NULL) {
29        if (current->key == key) {
30            current->value = value;
31            return;
32        }
33        current = current->next;
34    }
35    Node* newNode = createNode(key, value);
36    newNode->next = hashMap[hash];
37    hashMap[hash] = newNode;
38}
39
40int myHashMapGet(int key) {
41    int hash = hashFunction(key);
42    Node* current = hashMap[hash];
43    while (current != NULL) {
44        if (current->key == key) {
45            return current->value;
46        }
47        current = current->next;
48    }
49    return -1;
50}
51
52void myHashMapRemove(int key) {
53    int hash = hashFunction(key);
54    Node* current = hashMap[hash];
55    Node* prev = NULL;
56    while (current != NULL) {
57        if (current->key == key) {
58            if (prev != NULL) {
59                prev->next = current->next;
60            } else {
61                hashMap[hash] = current->next;
62            }
63            free(current);
64            return;
65        }
66        prev = current;
67        current = current->next;
68    }
69}The above C code initializes a simple hash table with separate chaining using linked lists. Each bucket of our hash table is a linked list to handle collisions.
hashFunction computes the index for a given key.createNode initializes a new linked list node.myHashMapPut inserts or updates a key-value pair.myHashMapGet retrieves the value for a corresponding key or returns -1 if not found.myHashMapRemove deletes a key and its associated value.Double hashing avoids the clustering problem by calculating two hash functions. If a collision occurs, a second hash determines the step size for probing.
Time Complexity: O(1) on average for put, get, and remove due to effective hashing; O(n) in worst-case.
Space Complexity: O(N) for storing entries with keys and values.
1#include
This C solution uses open addressing with double hashing. The second hash function provides an alternative probe sequence in case of collisions.
primaryHash and secondaryHash calculate indices.myHashMapPut uses the hashes to determine entry positions.myHashMapGet uses double hashing to locate the desired key.myHashMapRemove marks an entry as unoccupied upon deletion.