Leetcode之valid Parenttheses

26 June 2014

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.

解法：用栈存左括号，当匹配到右括号时弹出，如匹配不到，则结束返回错误。注意如果直接一个右括号时，栈顶没有元素。

代码如下：

//{java}
public class Solution {
    public boolean isValid(String s) {
       char stack[] = new char[10000];
       int top=0;
        for(int i=0;i<s.length();i++)
        {
           char c = s.charAt(i);
           if(c=='('||c=='{'||c=='[')
                stack[top++]=c;
            else
            {
                if(top==0||stack[top-1]!=other(c))
                    return false;
                else
                    top--;
            }
        }
        return top==0;
    }
    public char other(char c)
    {
        if(c==')')
             return '(';
        if(c==']')
             return '[';
        if(c=='}')
             return '{';
        return 0;
    }
}

LeetCode 47

LeetCode，面试，栈，括号合法 1

Leetcode之valid Parenttheses 括号合法问题

Valid Parentheses