LeetCode 20 Valid Parentheses

class Solution {
public:
    char a[10005];
    int pos=0;;
    bool isValid(string s) {
        
        if(s.length()==0)
            return true;
        for(int i=0;i<s.length();i++)
        {
            if(pos==0)
            {
                a[pos++]=s[i];
                continue;
            }
            else
            {
                if(a[pos-1]=='('&&s[i]==')')
                {
                    pos--;
                    continue;
                }
                else if(a[pos-1]=='['&&s[i]==']')
                {
                    pos--;
                    continue;
                }
                else if(a[pos-1]=='{'&&s[i]=='}')
                {
                    pos--;
                    continue;
                }
                else
                    a[pos++]=s[i];
                        
            }
        }
        if(pos!=0)
            return false;
        else
            return true;
        
    }
};