[Leetcode] valid parentheses

Valid parentheses

Given a string containing just the characters‘(‘,‘)‘,‘{‘,‘}‘,‘[‘And‘]‘, Determine if the input string is valid.

The brackets must close in the correct order,"()"And"()[]{}"Are all valid"(]"And"([)]"Are not.

 

Algorithm ideas:

This is a classic stack issue. I have adopted a large amount of data structures to ensure

The Code is as follows:

 1 public class Solution { 2     public boolean isValid(String s) { 3         if(s == null || (s.length() & 1 )== 1) return false; 4         Set<Character> leftSet = new HashSet<Character>(); 5         Set<Character> rightSet = new HashSet<Character>(); 6         char[] left = {‘(‘,‘[‘,‘{‘}; 7         char[] right = {‘)‘,‘]‘,‘}‘}; 8         Map<Character,Character> pair = new HashMap<Character,Character>(); 9         for(int i = 0; i < left.length;leftSet.add(left[i]),pair.put(left[i], right[i++]));10         for(int i = 0; i < right.length;rightSet.add(right[i++]));11         Stack<Character> stack = new Stack<Character>();12         for(int i = 0; i < s.length(); i++){13             char c = s.charAt(i);14             if(leftSet.contains(c)) {15                 stack.push(c);16             }else if(rightSet.contains(c)){17                 if(stack.isEmpty() || c != pair.get(stack.pop()) ) return false; 18             }19         }20          return stack.isEmpty();21     }22 }

In fact, it is completely necessary, but I have learned a better data structure.