發送短信 : The graph relabeling problem and its variants

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