字符串中的第一个唯一字符

 public int firstUniqChar(String s) {
		   if(s.equals("")) {
			   return -1;
		   }
		   char[] cArr = s.toCharArray();
		   int i;
		   int[] arr = new int[26];
		   ArrayList<Character> list = new ArrayList<>();
		   for(i = 0; i < cArr.length; i++) {
			   if(arr[cArr[i]-'a'] == 0) {
				   // 1.说明没有重复
				   list.add((Character)(cArr[i]));
				   arr[cArr[i]-'a']++;
			   }else {
				   //2. 有重复重新计数
				   list.remove((Character)(cArr[i]));
			   }
		   }
		   if(list.size() == 0) {
			   return -1;
		   }else {
			   
			   for ( i = 0; i < cArr.length; i++) {
				   if( cArr[i] == list.get(0)) {
					   return i;
				   }
			   }
			   return -1;
		   }

	   }

	   public int firstUniqChar(String s) {
		   int r = -1;
		   for(char c = 'a'; c <= 'z'; c++) {
			   int index = s.indexOf(c);
			   if(index != -1 && index == s.lastIndexOf(c)) {
				   r = r == -1 ? index : Integer.min(r, index);
			   }
		   }
		   return r;
	   }