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.