Balanced brackets

Validate (), [] and {}. Print -1 when valid; otherwise print the zero-based index of the first bad closing bracket, or the earliest opening bracket left unmatched at the end.

Input

— The first line contains T.
— Each case is one non-empty bracket string.

Output

Print the first bad index, or -1 when the string is balanced.

Technique

stack of token and index

Target

O(n) time · O(n) worst-case space

Constraints & sample

1 ≤ |s| ≤ 200,000
s contains only ()[]{}

Sample input

4
([]{})
([)]
(((
{[()]}

Expected output

-1
2
0
-1

Review the concept

Before you submit

Test the smallest valid input and one awkward edge case.
Keep the solution within O(n) time · O(n) worst-case space.
Match spacing and line breaks exactly before checking 10 hidden cases.

Draft saved locally · 356 / 30,000

Ln 1, Col 1Spaces: 4UTF-8LFC++17

Visible testcases

Editable and stored only in this browser. Hidden judge cases never change.

Input (stdin)Include T when the problem expects it

4
([]{})
([)]
(((
{[()]}

24 charsExpected outputExact output, ignoring trailing spaces

-1
2
0
-1

9 chars

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