求助：ACM题目

 
  The   2004   28   th   Annual   
  acm   
  International   Collegiate   
  Programming   Contest   World   Finals   
  sponsored   by   IBM   
  Problem   A   
  Carl   the   Ant   
  Input   File:   carl.in   
  Ants   leave   small   chemical   trails   on   the   ground   in   order   to   mark   paths   for   other   ants   to   follow.   Ordinarily   these   
  trails   follow   rather   straight   lines.   But   in   one   ant   colony   there   is   an   ant   named   Carl,   and   Carl   is   not   an   ordinary   
  ant.   Carl   will   often   zigzag   for   no   apparent   reason,   sometimes   crossing   his   own   path   numerous   times   in   the   
  process.   When   other   ants   come   to   an   intersection,   they   always   follow   the   path   with   the   strongest   scent,   which   is   
  the   most   recent   path   that   leads   away   from   the   intersection   point.   
  Ants   are   1   centimeter   long,   move   and   burrow   at   1   centimeter   per   second,   and   follow   their   paths   exactly   (bending   
  at   right   angles   when   moving   around   corners).   Ants   cannot   cross   or   overlap   each   other.   If   two   ants   meet   at   the   
  exact   same   instant   at   an   intersection   point,   the   one   that   has   been   on   Carl’s   path   the   longest   has   the   right   of   way;   
  otherwise,   the   ant   that   has   been   waiting   the   longest   at   an   intersection   will   move   first.   
  Carl   burrows   up   from   the   ground   to   start   at   the   origin   at   time   0.   He   then   walks   his   path   and   burrows   back   down   
  into   the   ground   at   the   endpoint.   The   rest   of   the   ants   follow   at   regular   intervals.   Given   the   description   of   Carl’s   
  path   and   when   the   other   ants   start   the   path,   you   are   to   determine   how   long   it   takes   the   entire   set   of   ants   to   finish   
  burrowing   back   into   the   ground.   All   the   ants   are   guaranteed   to   finish.   
  Input   
  Input   consists   of   several   test   cases.   The   first   line   of   the   input   file   contains   a   single   integer   indicating   the   number   
  of   test   cases.   
  The   input   for   each   test   case   starts   with   a   single   line   containing   three   positive   integers   n   (1   ≤n   ≤50),   
  m   (1   ≤m   ≤100),   and   d   (1   ≤d   ≤100).   Here,   n   is   the   number   of   line   segments   in   Carl’s   path,   m   is   the   number   of   
  ants   traveling   the   path   (including   Carl),   and   d   is   the   time   delay   before   each   successive   ant’s   emergence.   Carl   
  (who   is   numbered   0)   starts   at   time   0.   The   next   ant   (ant   number   1)   will   emerge   at   time   d,   the   next   at   time   2d,   and   
  so   on.   If   the   burrow   is   blocked,   the   ants   will   emerge   as   soon   as   possible   in   the   correct   order.   
  Each   of   the   next   n   lines   for   the   test   case   consists   of   a   unique   integer   pair   x   y   (-100   ≤x,   y   ≤100),   which   is   the   
  endpoint   of   a   line   segment   of   Carl’s   path,   in   the   order   that   Carl   travels.   The   first   line   starts   at   the   origin   (0,0)   and   
  the   starting   point   of   every   subsequent   line   is   the   endpoint   of   the   previous   line.   
  For   simplicity,   Carl   always   travels   on   line   segments   parallel   to   the   axes,   and   no   endpoints   lie   on   any   segment   
  other   than   the   ones   which   they   serve   as   an   endpoint.   
  Output   
  The   output   for   each   case   is   described   as   follows:   
  Case   C:   Carl   finished   the   path   at   time   t1   The   ants   finished   in   the   following   order:   a1   a2   a3   ...   am   The   last   ant   finished   the   path   at   time   t2   
  Here,   C   is   the   case   number   (starting   at   1),   a1   ,   a2   ,   a3   ,   …   am   are   the   ant   numbers   in   the   order   that   they   go   
  back   underground,   and   t1   and   t2   are   the   times   (in   seconds)   at   which   Carl   and   the   last   ant   finish   going   
  underground.   You   should   separate   consecutive   cases   with   a   single   blank   line.   
    
  Sample   Input   Output   for   the   Sample   Input   
  2   4   7   4   0   4   2   4   2   2   -2   2   4   7   2   0   4   2   4   2   2   -2   2   
  Case   1:   Carl   finished   the   path   at   time   13   The   ants   finished   in   the   following   order:   0   2   1   3   4   5   6   The   last   ant   finished   the   path   at   time   29   
  Case   2:   Carl   finished   the   path   at   time   13   The   ants   finished   in   the   following   order:   0   4   1   5   2   6   3   The   last   ant   finished   the   path   at   time   19