Valid Parentheses — interactive algorithm visualization
Easy · Stack · time O(n) · space O(n)
The canonical stack problem. The top of the stack is always the bracket that must close next; the string is valid only if the stack empties.
Example input: s = "([{}])"
Step through a verified execution trace - every step shows the real state, the invariant that keeps the algorithm correct, and asks you to predict what happens next.
Solve Valid Parentheses in the editor · All 16 visualizations