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116 lines
3.3 KiB
Markdown
116 lines
3.3 KiB
Markdown
---
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id: 68d30fc57588d97fd3027b30
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title: "Challenge 79: Navigator"
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challengeType: 29
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dashedName: challenge-79
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---
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# --description--
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On October 28, 1994, Netscape Navigator was released, helping millions explore the early web.
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Given an array of browser commands you executed on Netscape Navigator, return the current page you are on after executing all the commands using the following rules:
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- You always start on the `"Home"` page, which will not be included in the commands array.
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- Valid commands are:
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- `"Visit Page"`: Where `"Page"` is the name of the page you are visiting. For example, `"Visit About"` takes you to the `"About"` page. When you visit a new page, make sure to discard any forward history you have.
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- `"Back"`: Takes you to the previous page in your history or stays on the current page if there isn't one.
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- `"Forward"`: Takes you forward in the history to the page you came from or stays on the current page if there isn't one.
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For example, given `["Visit About Us", "Back", "Forward"]`, return `"About Us"`.
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# --hints--
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`navigate(["Visit About Us", "Back", "Forward"])` should return `"About Us"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Visit About Us", "Back", "Forward"]), "About Us")`)
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}})
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```
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`navigate(["Forward"])` should return `"Home"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Forward"]), "Home")`)
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}})
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```
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`navigate(["Back"])` should return `"Home"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Back"]), "Home")`)
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}})
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```
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`navigate(["Visit About Us", "Visit Gallery"])` should return `"Gallery"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Visit About Us", "Visit Gallery"]), "Gallery")`)
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}})
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```
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`navigate(["Visit About Us", "Visit Gallery", "Back", "Back"])` should return `"Home"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Visit About Us", "Visit Gallery", "Back", "Back"]), "Home")`)
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}})
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```
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`navigate(["Visit About", "Visit Gallery", "Back", "Visit Contact", "Forward"])` should return `"Contact"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Visit About", "Visit Gallery", "Back", "Visit Contact", "Forward"]), "Contact")`)
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}})
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```
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`navigate(["Visit About Us", "Visit Visit Us", "Forward", "Visit Contact Us", "Back"])` should return `"Visit Us"`.
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```js
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({test: () => { runPython(`
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from unittest import TestCase
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TestCase().assertEqual(navigate(["Visit About Us", "Visit Visit Us", "Forward", "Visit Contact Us", "Back"]), "Visit Us")`)
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}})
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```
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# --seed--
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## --seed-contents--
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```py
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def navigate(commands):
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return commands
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```
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# --solutions--
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```py
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def navigate(commands):
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history = ["Home"]
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current_index = 0
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for command in commands:
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if command.startswith("Visit "):
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history = history[:current_index + 1]
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history.append(command[6:])
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current_index += 1
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elif command == "Back" and current_index > 0:
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current_index -= 1
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elif command == "Forward" and current_index < len(history) - 1:
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current_index += 1
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return history[current_index]
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```
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