發送短信 : Linear complexity, k-error linear complexity, and the discrete Fourier transform

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