Valid Parentheses
Part of Practice: Classic Stacks
Given a string s made only of the six bracket characters ()[]{}, decide whether it is properly balanced. Balanced means every opening bracket is closed by the same type of bracket, in the correct order — each closer matches the most recently opened, still-unclosed bracket.
The string can be up to 10^4 characters. Note that an empty stack of pending brackets at the end is part of being valid: "(" alone is not balanced.
Examples
- Input:
- s = "()[]{}"
- Output:
- true
Three pairs, each closed immediately in the right order.
- Input:
- s = "(]"
- Output:
- false
The ] tries to close a ( — wrong bracket type.
- Input:
- s = "([)]"
- Output:
- false
The ) arrives while [ is the most recent open bracket, so the nesting order is wrong. "([])" would be fine.
Hints
One at a time — struggle first, peek second.
Your thinking space — verify on LeetCode, then mark it.