發送短信 : The graph relabeling problem and its variants

 __   __     ___      ______   _    _     ______  
 \ \\/ //   / _ \\   /_____// | || | ||  /_   _// 
  \   //   / //\ \\  `____ `  | || | ||  `-| |,-  
  / . \\  |  ___  || /___//   | \\_/ ||    | ||   
 /_//\_\\ |_||  |_|| `__ `     \____//     |_||   
 `-`  --` `-`   `-`  /_//       `---`      `-`'   
                     `-`