public static String largestNumber(int[] nums) {
    StringBuffer sb = new StringBuffer();
    qsort(nums);
    int i = 0;
    for (i = 0; i < nums.length; i++) {
      if (nums[i] != 0) break;
    }
    for (; i < nums.length; i++) {
      sb.append(nums[i]);
    }
    String res = sb.toString();
    return (res == null || res.compareTo("") == 0) ? "0" : res;
  }