Glasgow | 26-Jul-SDC | Shreef Ibrahim | Sprint 2 |ImplementSikplist

Sprint-2/implement_skip_list/skip_list.py

@@ -0,0 +1,74 @@
+import random
+
+class _Node:
+    def __init__(self, value, level):
+        self.value = value
+        self.forward = [None] * (level + 1)
+
+class SkipList:
+    MAX_LEVEL = 16
+    P = 0.5
+
+    def __init__(self):
+        self.level = 0
+        self.head = _Node(None, self.MAX_LEVEL)
+
+    def _random_level(self):
+        level = 0
+        while random.random() < self.P and level < self.MAX_LEVEL:
+            level += 1
+        return level
+
+    def insert(self, value):
+        update = [None] * (self.MAX_LEVEL + 1)
+        current = self.head
+
+        for i in range(self.level, -1, -1):
+            while (
+                current.forward[i] is not None
+                and current.forward[i].value < value
+            ):
+                current = current.forward[i]
+            update[i] = current
+
+        current = current.forward[0]
+
+        if current is not None and current.value == value:
+            return
+
+        new_level = self._random_level()
+
+        if new_level > self.level:
+            for i in range(self.level + 1, new_level + 1):
+                update[i] = self.head
+            self.level = new_level
+
+        node = _Node(value, new_level)
+
+        for i in range(new_level + 1):
+            node.forward[i] = update[i].forward[i]
+            update[i].forward[i] = node
+
+    def __contains__(self, value):
+        current = self.head
+
+        for i in range(self.level, -1, -1):
+            while (
+                current.forward[i] is not None
+                and current.forward[i].value < value
+            ):
+                current = current.forward[i]
+
+        current = current.forward[0]
+
+        return current is not None and current.value == value
+
+    def to_list(self):
+        result = []
+        current = self.head.forward[0]
+
+        while current is not None:
+            result.append(current.value)
+            current = current.forward[0]
+
+        return result

Sprint-2/improve_with_precomputing/common_prefix/common_prefix.py

@@ -1,24 +1,38 @@
+
 from typing import List
 
 
-def find_longest_common_prefix(strings: List[str]):
+def find_longest_common_prefix(strings: List[str]) -> str:
     """
-    find_longest_common_prefix returns the longest string common at the start of any two strings in the passed list.
-
-    In the event that an empty list, a list containing one string, or a list of strings with no common prefixes is passed, the empty string will be returned.
+    Return the longest common prefix shared by any two strings.
+    Return an empty string if fewer than two strings are provided
+    or no non-empty common prefix exists.
     """
+    if len(strings) < 2:
+        return ""
+
+    # Precompute the sorted order to avoid comparing every pair
+    ordered_strings = sorted(strings)
+
     longest = ""
-    for string_index, string in enumerate(strings):
-        for other_string in strings[string_index+1:]:
-            common = find_common_prefix(string, other_string)
-            if len(common) > len(longest):
-                longest = common
+
+    for index in range(len(ordered_strings) - 1):
+        common = find_common_prefix(
+            ordered_strings[index],
+            ordered_strings[index + 1]
+        )
+
+        if len(common) > len(longest):
+            longest = common
+
     return longest
 
 
 def find_common_prefix(left: str, right: str) -> str:
-    min_length = min(len(left), len(right))
-    for i in range(min_length):
-        if left[i] != right[i]:
-            return left[:i]
-    return left[:min_length]
+    limit = min(len(left), len(right))
+
+    for index in range(limit):
+        if left[index] != right[index]:
+            return left[:index]
+
+    return left[:limit]