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1472. Design Browser History.py
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1472. Design Browser History.py
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from collections import deque as dq
class BrowserHistory:
def __init__(self, homepage: str):
self.history = [homepage]
self.current_page = 0
def visit(self, url: str) -> None:
self.history.insert(self.current_page+1, url)
self.history = self.history[:self.current_page+2]
self.current_page = len(self.history)-1
def back(self, steps: int) -> str:
backward = self.history[:self.current_page+1].copy()
if steps>=len(backward):
self.current_page = 0
return self.history[0]
while backward:
backward.pop()
steps -= 1
if steps==0:
try:
self.current_page = len(backward)-1
return backward[-1]
except IndexError:
return self.history[0]
def forward(self, steps: int) -> str:
s = steps
forward = dq(self.history[self.current_page:].copy())
if steps>=len(forward):
self.current_page = len(self.history)-1
return self.history[-1]
while forward:
forward.popleft()
steps -= 1
if steps==0:
try:
self.current_page += s
return forward[0]
except IndexError:
return self.history[len(self.history)-1]
# Your BrowserHistory object will be instantiated and called as such:
# obj = BrowserHistory(homepage)
# obj.visit(url)
# param_2 = obj.back(steps)
# param_3 = obj.forward(steps)