Merge pull request neetcode-gh#1243 from hrishikeshtak/main

Create: 1472-Design-Browser-History.py

python/1472-Design-Browser-History.py

@@ -0,0 +1,57 @@
+"""
+1472. Design Browser History
+"""
+
+
+class DLLNode:
+ def __init__(self, val):
+ self.val = val
+ self.prev = None
+ self.next = None
+
+
+class BrowserHistory:
+ def __init__(self, homepage: str):
+ # initialize head and tail to dummy node
+ self.head = DLLNode(-1)
+ self.tail = DLLNode(-1)
+
+ self.head.next = self.tail
+ self.tail.prev = self.head
+
+ # insert homepage at head node
+ self.insertAtHead(homepage)
+ # update cur pointer to homepage
+ self.cur = self.head.next
+
+ def insertAtHead(self, homepage: str):
+ temp = DLLNode(homepage)
+ temp.next = self.head.next
+ temp.prev = self.head
+
+ self.tail.prev = temp
+ self.head.next = temp
+
+ def visit(self, url: str) -> None:
+ temp = DLLNode(url)
+ # clears forward history
+ temp.next = self.tail
+ temp.prev = self.cur
+ self.tail.prev = temp
+ self.cur.next = temp
+ # update cur pointer to URL
+ self.cur = self.cur.next
+
+ def back(self, steps: int) -> str:
+ i = 0
+ while self.cur.prev != self.head and i < steps:
+ self.cur = self.cur.prev
+ i += 1
+ return self.cur.val
+
+ def forward(self, steps: int) -> str:
+ i = 0
+ while self.cur.next != self.tail and i < steps:
+ self.cur = self.cur.next
+ i += 1
+ return self.cur.val