發送短信 : The graph relabeling problem and its variants

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