adds challenge 30 files

class-30/challenge/hashtable.py

@@ -0,0 +1,92 @@
+from data_structures.linked_list import LinkedList
+
+
+class Hashtable:
+    """
+    Put docstring here
+    """
+
+    def __init__(self, size=1024):
+        self._size = size
+        self._buckets = [None] * size
+
+    def set(self, key, value):
+        index = self._hash(key)
+        bucket = self._buckets[index]
+        if bucket is None:
+            bucket = LinkedList()
+            self._buckets[index] = bucket
+
+        current = bucket.head
+
+        while current:
+            candidate_drop = current.value
+            if candidate_drop[0] == key:
+                # found preexisting drop
+                candidate_drop[1] = value  # update the value
+                return
+
+        drop = [key, value]  # no prexisting drop, add the drop aka key-value pair
+        bucket.insert(drop)
+
+    def get(self, key):
+        index = self._hash(key)
+
+        bucket = self._buckets[index]
+
+        if bucket is None:
+            return None
+
+        current = bucket.head
+
+        while current:
+            drop = current.value  # key value pair
+            if drop[0] == key:
+                return drop[1]
+
+            current = current.next
+
+        return None
+
+    def keys(self):
+        """
+        return list of keys
+        """
+        key_list = []  # list of strings
+
+        for bucket in self._buckets:  # list of LinkedLists (or None)
+            if bucket:  # LinkedList
+                current = bucket.head  # Node
+                while current:
+                    drop = current.value  # List of 2 items [key, value]
+                    key_list.append(drop[0])
+                    current = current.next
+
+        return key_list
+
+    def has(self, key):
+        for bucket in self._buckets:  # list of LinkedLists (or None)
+            if bucket:  # LinkedList
+                current = bucket.head  # Node
+                while current:
+                    drop = current.value  # List of 2 items [key, value]
+                    if drop[0] == key:
+                        return True
+
+                    current = current.next
+
+        return False
+
+    def _hash(self, key):
+        """
+        Add all the ASCII values together.
+        Multiply it by a prime number such as 599.
+        Use modulo to get the remainder of the result, when divided by the total size of the array.
+        """
+        index = 0
+        for char in key:
+            index += ord(char)
+        index *= 599
+        index = index % self._size
+
+        return index

class-30/challenge/test_hashtable.py

@@ -0,0 +1,107 @@
+import pytest
+from data_structures.hashtable import Hashtable
+
+
+def test_exists():
+    assert Hashtable
+
+
+@pytest.mark.skip("TODO")
+def test_hash():
+    """
+    NOTE: intentionally breaks "encapsulation" by accessing "internal" attriubutes
+    """
+    hashtable = Hashtable()
+    actual = hashtable._hash("Zach")
+    assert 0 <= actual < hashtable._size
+
+
+@pytest.mark.skip("TODO")
+def test_hash_twice():
+    """
+    NOTE: intentionally breaks "encapsulation" by accessing "internal" attriubutes
+    """
+    hashtable = Hashtable()
+    first = hashtable._hash("Zach")
+    second = hashtable._hash("Zach")
+    assert first == second
+
+
+@pytest.mark.skip("TODO")
+def test_apple():
+    hashtable = Hashtable()
+    hashtable.set("apple", "Used for apple sauce")
+    actual = hashtable.get("apple")
+    expected = "Used for apple sauce"
+    assert actual == expected
+
+
+@pytest.mark.skip("TODO")
+def test_apple_again():
+    hashtable = Hashtable()
+    hashtable.set("apple", "Used for apple sauce")
+    hashtable.set("apple", "Can give to teacher")
+    actual = hashtable.get("apple")
+    expected = "Can give to teacher"
+    assert actual == expected
+
+
+@pytest.mark.skip("TODO")
+def test_key_not_exists():
+    hashtable = Hashtable()
+    actual = hashtable.get("nonexisting key")
+    expected = None
+    assert actual == expected
+
+
+@pytest.mark.skip("TODO")
+def test_key_not_exists_again():
+    """
+    WARNING: requires that act & cat hash the same
+    """
+    hashtable = Hashtable()
+    hashtable.set("cat", "meow")
+    actual = hashtable.get("act")
+    expected = None
+    assert actual == expected
+
+
+@pytest.mark.skip("TODO")
+def test_keys():
+    hashtable = Hashtable()
+    hashtable.set("apple", "Used for apple sauce")
+    hashtable.set("banana", "Great in a banana split")
+    actual = hashtable.keys()
+    expected = ["apple", "banana"]
+    assert sorted(actual) == sorted(expected)
+
+
+@pytest.mark.skip("TODO")
+def test_has():
+    hashtable = Hashtable()
+    hashtable.set("apple", "Used for apple sauce")
+    hashtable.set("banana", "Great in a banana split")
+    assert hashtable.has("apple")
+    assert hashtable.has("banana")
+    assert not hashtable.has("cucumber")
+
+
+@pytest.mark.skip("TODO")
+def test_keys_repeats():
+    hashtable = Hashtable()
+    hashtable.set("apple", "Used for apple sauce")
+    hashtable.set("apple", "Can give to teacher")
+    hashtable.set("banana", "Great in a banana split")
+    actual = hashtable.keys()
+    expected = ["apple", "banana"]
+    assert sorted(actual) == sorted(expected)
+
+
+@pytest.mark.skip("TODO")
+def test_internals():
+    """
+    NOTE: there's a test_internals in your DSA repo that isn't a great fit.
+    Feel free to ignore it
+    Or tweak it as a STRETCH
+    """
+    pass