JavaMediumStack & Queue20 min
Validate balanced brackets
Print true if every closing bracket matches the most recent unmatched opening bracket and no openings remain. Follow the stated ordering and edge-case conventions exactly. Interviewers use this task to probe algorithm selection, invariants, and boundary handling.
Input
One line containing only (), [], and {}, possibly empty.
Output
Print true if every closing bracket matches the most recent unmatched opening bracket and no openings remain.
Constraints
0 <= length <= 100000.
Example
Input
{[()]}Output
true
Example 2 input
}{Output
false
This example exercises a further boundary or ordering case.
Public test cases (2)
Input
{[()]}Expected output
true
Input
([)]
Expected output
false
Hints (2)
- Identify the state needed to avoid recomputing work for each element.
- Use an ArrayDeque as a stack to enforce last-opened, first-closed matching.
Target complexity: time O(n) · space O(n)