字符流中第一个不重复的字符

 

class Solution
{
public:
  //Insert one char from stringstream
    Solution():index_(0)
        {
        for(int i=0;i<256;i++)
            {
            ascii[i]=-1;
        }
    }
    void Insert(char ch)
    {
         if(ascii[ch]==-1)
             ascii[ch]=index_;
         else if(ascii[ch]>=0)
            ascii[ch]=-2;
             index_++;
    }
  //return the first appearence once char in current stringstream
    char FirstAppearingOnce()
    {
      int minIndex=65535;
      char ch='#';
        for(int i=0;i<256;i++)
            {
            if(ascii[i]>=0&&minIndex>ascii[i])
                {
                ch=(char)i;
                minIndex=ascii[i];
            }
        }   
        return ch;
      
    }
private:
    int ascii[256];
    int index_;
};