RAII Release Order

In C++, RAII ties a resource to an object's lifetime: the resource is released automatically when the object goes out of scope. Objects in the same scope are destroyed in reverse order of creation.

Process the events in order:

• {: enter a new inner scope.
• }: leave the current scope; every resource acquired in it is released, newest first.
• acquire <name>: create a resource in the current scope.

When the events run out, the remaining open scopes end from the innermost to the outermost (the program's outer scope included), releasing their resources the same way.

Implement raii_release_order(events).

Input

events: The events. Braces are balanced or left open, never closed without being opened.

Output

Return the resource names in the order they are released.

เงื่อนไข

0 ≤ number of events ≤ 100,000

Names have 1 to 20 characters without spaces

ตัวอย่าง

อินพุต:
events = ["acquire db", "{", "acquire file", "acquire lock", "}", "acquire log"]

ผลลัพธ์ที่คาดหวัง:
expected = ["lock", "file", "log", "db"]

อินพุต:
std::vector<std::string> events = {"acquire db", "{", "acquire file", "acquire lock", "}", "acquire log"};

ผลลัพธ์ที่คาดหวัง:
std::vector<std::string> expected = {"lock", "file", "log", "db"};

อินพุต:
string[] events = new string[] {"acquire db", "{", "acquire file", "acquire lock", "}", "acquire log"};

ผลลัพธ์ที่คาดหวัง:
string[] expected = new string[] {"lock", "file", "log", "db"};

อินพุต:
events = ["{", "acquire a", "{", "acquire b"]

ผลลัพธ์ที่คาดหวัง:
expected = ["b", "a"]

อินพุต:
std::vector<std::string> events = {"{", "acquire a", "{", "acquire b"};

ผลลัพธ์ที่คาดหวัง:
std::vector<std::string> expected = {"b", "a"};

อินพุต:
string[] events = new string[] {"{", "acquire a", "{", "acquire b"};

ผลลัพธ์ที่คาดหวัง:
string[] expected = new string[] {"b", "a"};

แหล่งอ้างอิง

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• cppreference, RAII