leetcode-192周赛-1472-设计浏览器历史记录

class BrowserHistory:

    def __init__(self, homepage: str):
        self.list = [homepage]
        self.cur = 0

    def visit(self, url: str) -> None:
        if self.cur == len(self.list) - 1:
            self.list.append(url)
        else: 
            self.list[self.cur + 1:] = [url]
        self.cur += 1


    def back(self, steps: int) -> str:
        if self.cur - steps < 0:
            self.cur = 0
        else:
            self.cur -= steps
        return self.list[self.cur]

    def forward(self, steps: int) -> str:
        if self.cur + steps >= len(self.list) - 1:
            self.cur = len(self.list) - 1
        else:
            self.cur += steps
        return self.list[self.cur]