python写算法题：leetcode: 20. Valid Parentheses

https://leetcode.com/problems/valid-parentheses/#/description

class Solution(object):
    def isValid(self, s):
        """
        :type s: str
        :rtype: bool
        """
        stab='(){}[]'
        tab=[0]*(len(stab)/2)
        pos=0
        smap={}
        ssig={}
        fills=[]
        for c in stab:
            smap[c]=pos/2
            ssig[c]=1-2*(pos%2)
            pos+=1
        for c in s:
            pos=smap[c]
            tab[pos]+=ssig[c]
            if ssig[c]<0:
                if len(fills)==0 or fills[-1]!=pos:
                    return False
                fills=fills[:-1]
            else:
                fills.append(pos)
        if len(fills)!=0: return False
        return True