单点时限: 2.0 sec
内存限制: 256 MB
A bracket is considered to be any one of the following characters: (, ), {, }, [, or ].
Two brackets are considered to be a matched pair if the an opening bracket (, [, or { occurs to the left of a closing bracket ), ], or } of the exact same type. There are three types of matched pairs of brackets: [ ], { }, and ( ).
A matching pair of brackets is not balanced if the set of brackets it encloses are not matched. For example, {[(])} is not balanced because the contents in between { and } are not balanced. The pair of square brackets encloses a single, unbalanced opening bracket, (, and the pair of parentheses encloses a single, unbalanced closing square bracket, ].
By this logic, we say a sequence of brackets is considered to be balanced if the following conditions are met:
Given strings of brackets, determine whether each sequence of brackets is balanced. If a string is balanced, print YES on a new line; otherwise, print NO on a new line.
The first line contains a single integer, $n$, denoting the number of strings.
Each line $i$ of the $n$ subsequent lines consists of a single string, $s$, denoting a sequence of brackets.
{, }, (, ), [, and ]).For each string, print whether or not the string of brackets is balanced on a new line. If the brackets are balanced, print YES; otherwise, print NO.
3
{[()]}
{[(])}
{{[[(())]]}}
YES NO YES
The string {[()]} meets both criteria for being a balanced string, so we print YES on a new line.
The string {[(])} is not balanced, because the brackets enclosed by the matched pairs [(] and (]) are not balanced.
The string {{[[(())]]}} meets both criteria for being a balanced string, so we print YES on a new line.