Update and rename 1472-Design-Browser-History.py to 1472-design-browser-history.py

Author: neetcode-gh

python/1472-Design-Browser-History.py

@@ -0,0 +1,57 @@
+# Linked List Implementation
+class ListNode:
+    def __init__(self, val, prev=None, next=None):
+        self.val = val
+        self.prev = prev
+        self.next = next
+
+class BrowserHistory:
+
+    def __init__(self, homepage: str):
+        self.cur = ListNode(homepage)
+
+    # O(1)
+    def visit(self, url: str) -> None:
+        self.cur.next = ListNode(url, self.cur)
+        self.cur = self.cur.next
+
+    # O(n)
+    def back(self, steps: int) -> str:
+        while self.cur.prev and steps > 0:
+            self.cur = self.cur.prev
+            steps -= 1
+        return self.cur.val
+
+    # O(n)
+    def forward(self, steps: int) -> str:
+        while self.cur.next and steps > 0:
+            self.cur = self.cur.next
+            steps -= 1
+        return self.cur.val
+
+
+# Array Implementation
+class BrowserHistory:    
+    def __init__(self, homepage: str):
+        self.i = 0
+        self.len = 1
+        self.history = [homepage]
+
+    # O(1)
+    def visit(self, url: str) -> None:
+        if len(self.history) < self.i + 2:
+            self.history.append(url)
+        else:
+            self.history[self.i + 1] = url
+        self.i += 1
+        self.len = self.i + 1
+
+    # O(1)
+    def back(self, steps: int) -> str:
+        self.i = max(self.i - steps, 0)
+        return self.history[self.i]
+
+    # O(1)
+    def forward(self, steps: int) -> str:
+        self.i = min(self.i + steps, self.len - 1)
+        return self.history[self.i]