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 but "(]" and "([)]" are not.

public class Solution {
   public boolean isValid(String s) {
        if(s.length() % 2 == 1)//个数为奇数返回false
            return false;
        char stack[] = new char[s.length() / 2];
//        boolean isValid = true;
        int top = -1;//栈顶
        stack[++top] = s.charAt(0);
        
        for(int i = 1; i < s.length(); i++){//遍历完成
            
            if('(' == s.charAt(i) || '[' == s.charAt(i) || '{' == s.charAt(i)){//入栈
                if(top >= stack.length - 1)//左括号个数大于右括号个数
                    return false;
                stack[++top] = s.charAt(i);
            }
            else{
                if(-1 == top){//如果栈已经空了
                    return false;
                }
                char temp = stack[top--];//出栈
                switch(s.charAt(i)){
                    case ')':
                        if(temp != '(')
                            return false;
                        break;
                    case ']':
                        if(temp != '[')
                            return false;
                        break;
                    case '}':
                        if(temp != '{')
                            return false;
                }
            }
        }
        if(-1 == top)//栈为空
            return true;
        return false;//栈不空
    }
}