Stacks: Balanced Brackets
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 (i.e., (, [, or {) occurs to the left of a closing bracket (i.e., ), ], 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, ].
Some examples of balanced brackets are []{}(), [({})]{}() and ({(){}[]})[].
By this logic, we say a sequence of brackets is considered to be balanced if the following conditions are met:
- It contains no unmatched brackets.
- The subset of brackets enclosed within the confines of a matched pair of brackets is also a matched pair of brackets.
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.
Input Format
The first line contains a single integer, , denoting the number of strings.
Each line of the subsequent lines consists of a single string, , denoting a sequence of brackets.
Constraints
- , where is the length of the sequence.
- Each character in the sequence will be a bracket (i.e.,
{,},(,),[, and]).
Output Format
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.
Sample Input
3
{[()]}
{[(])}
{{[[(())]]}}
Sample Output
YES
NO
YES
Explanation
- The string
{[()]}meets both criteria for being a balanced string, so we printYESon a new line. - The string
{[(])}is not balanced, because the brackets enclosed by the matched pairs[(]and(])are not balanced. Thus, we printNOon a new line. - The string
{{[[(())]]}}meets both criteria for being a balanced string, so we printYESon a new line.