[feature] add hashmap category

Author: gitgik

README.md

@@ -94,6 +94,10 @@ A catalogue of data structures implementation + algorithms and coding problems a
 - [Single cycle check](graphs/single_cycle_check.md)
 - [Youngest common ancestor](graphs/youngest_common_ancestor.md)
 
+## Hashmaps
+
+- [Hashmap implementation](hash-maps/hash_map.md)
+
 ## Heaps
 
 - [Given buildings, model a skyline](heaps/max_heap_skyline.md)

hash-maps/hash_map.md

@@ -0,0 +1,86 @@
+```python
+class HashMap:
+    def __init__(self, size):
+        self.size = size
+        self.hash_table = self.createBuckets()
+        
+    def createBuckets(self):
+        return [[] for i in range(self.size)]
+    
+    def set(self, key, value):
+        # get bucket hash
+        bucket_hash = hash(key) % self.size
+        bucket = self.hash_table[bucket_hash]
+        
+        found_key = False
+        for idx, record in enumerate(bucket):
+            record_key, record_val = record
+            if record_key == key:
+                found_key = True
+                break
+        if found_key:
+            bucket[idx] = (key, value)
+        else:
+            bucket.append((key, value))
+    
+    def get(self, key):
+        # Get the index of the bucket holding the key using the hash function
+        index = hash(key) % self.size
+        
+        # get the bucket using the index
+        bucket = self.hash_table[index]
+        
+        found_key = False
+        for idx, record in enumerate(bucket):
+            record_key, record_val = record
+            if key == record_key:
+                found_key = True
+                break
+        return record_val if found_key else None
+    
+    def delete(self, key):
+        bucket_hash = hash(key) % self.size
+        found_key = False
+        for idx, record in enumerate(self.hash_table[bucket_hash]):
+            record_key, record_value = record
+            if key == record_key:
+                found_key = True
+                break
+        if found_key:
+            # delete
+            self.hash_table.pop(idx)
+        else:
+            return f"Key '{key}' does not exist"
+            
+        
+```
+
+
+```python
+hashmap = HashMap(10)
+```
+
+
+```python
+hashmap.set("something", "soweto")
+for i in range(5):
+    hashmap.set(f"{i}", i)
+```
+
+
+```python
+hashmap.get("something")
+
+```
+
+
+
+
+    'soweto'
+
+
+
+
+```python
+
+```