- Practice
- Interview Preparation Kits
- 1 Week Preparation Kit
- Day 5
- Balanced Brackets

# Balanced Brackets

# 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, `]`

.

By this logic, we say a sequence of brackets is *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, return `YES`

. Otherwise, return `NO`

.

**Function Description**

Complete the function *isBalanced* in the editor below.

isBalanced has the following parameter(s):

*string s*: a string of brackets

**Returns**

*string:*either`YES`

or`NO`

**Input Format**

The first line contains a single integer , the number of strings.

Each of the next lines contains a single string , a sequence of brackets.

**Constraints**

- , where is the length of the sequence.
- All chracters in the sequences ∈ {
**{**,**}**,**(**,**)**,**[**,**]**}.

**Output Format**

For each string, return `YES`

or `NO`

.

**Sample Input**

STDIN Function ----- -------- 3 n = 3 {[()]} first s = '{[()]}' {[(])} second s = '{[(])}' {{[[(())]]}} third s ='{{[[(())]]}}'

**Sample Output**

```
YES
NO
YES
```

**Explanation**

- The string
`{[()]}`

meets both criteria for being a balanced string. - The string
`{[(])}`

is not balanced because the brackets enclosed by the matched pair`{`

and`}`

are not balanced:`[(])`

. - The string
`{{[[(())]]}}`

meets both criteria for being a balanced string.