public static int stringConstruction(String s) {
    HashMap<Character, Integer> countChar = new HashMap<Character, Integer>();
    char[] s_char = s.toCharArray();
    for(int i=0; i<s.length(); i++)
    {
        if(!countChar.containsKey(s_char[i]))    
        {
            countChar.put(s_char[i],1);
        }
    }
    return countChar.size();
    }

function stringConstruction(s) {
    return new Set([...s]).size
}

function stringConstruction(s) {
  let [i, sLength, cost] = [0, s.length, 0];
  while (i < sLength) {
    if (!s.slice(0, i).includes(s[i])) cost++;
    i++;
  }
  return cost;
}

int stringConstruction(char* s)
{
    int max=0;int count=0;
    for( int i = 0 ; i<strlen(s);i++)
    {
       if(s[i]>max)
       {
           max = s[i];
       }
        
    }
    int *arr = (int*)calloc(max+1,sizeof(int));
    
 for(int i = 0 ; i<strlen(s);i++)
    {
      arr[s[i]]++;        
    }
  for(int i = 0 ; i<=max;i++)
    {
      if(arr[i]>0)
      {
          count++;
          arr[i]=0;
      }
    }  
    free(arr);
    return count;

}