offer_50

//面试题50：第一个只出现一次的字符
//题目1：字符串中第一个只出现一次的字符
char FirstNotReapting(char* pString)
{
  if(pString==nullptr)
    return '\0';
  const int tableSize=256;
  unsigned int hashTable[tableSize];
  for(unsigned int i=0;i<tableSize;++i){
    hashTable[i]=0;
  }
  
  char* pHashKey=pString;
  while(*(pHashKey)!='\0')
    hash[*(pHashKey++)]++;
   pHashKey=pString;
   while(*pHashKey!='\0'){
    if(hashTable[*pHashKey]==1)
      return *pHashKey;
     
    pHashKey++;
   }
  }
  return '\0';
}

//题目2：字符流中第一个只出现一次的字符
class CharStatics
{
  public:
    CharStatics():index(0)
    {
      for(int i=0;i<256;++i)
        occurrence[i]=-1;
    }
    
    void Insert(char ch)
    {
      if(occurrence[ch]=-1)
        occurence[ch]=index;
      else if(occurence[ch]>=0)
        occurence[ch]=-2;
       
       index++;
    }
    
    char FirstApperaringOnce()
    {
      char ch='\0';
      int minIndex=numeric_limit<int>::max(); //表示int类型的最大值
      for(int i=0;i<256;++i){
        if(occurence[i]>=0 && occurence[i]<minIndex){
          ch=(char)i;
          minIndex=occurence[i];
        }
      }
      return ch;
    }
    
   private:
    int occurence[256];
    int index;
    
}