Given a string containing just the characters
']', determine if the input string is valid.
An input string is valid if:
- Open brackets must be closed by the same type of brackets.
- Open brackets must be closed in the correct order.
Note that an empty string is also considered valid.
right are lists.
mapping is a dictionary, which combines
zip function. Searching/matching in dictionary would be more efficient than in list.
Pythonic way to express checking:
If s[i] is not ‘)’,’}’,’]’, then stack.append(s[i]); if s[i] is ‘)’,’}’,’]’, then compare it with stack.pop() — the top element in stack. Concise code speeds the execution…
Too many “if” checks slow the solution.
This check above for test case without left brackets:
This check above for test case in disorder: