| 1 | #include <fstream.hfa>                                                                  // sin/sout | 
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| 2 | #include <stdlib.hfa>                                                                   // convert | 
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| 3 | #include <string.h> | 
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| 4 | #include <coroutine.hfa> | 
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| 5 |  | 
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| 6 | struct Potato { | 
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| 7 | PRNG & prng; | 
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| 8 | unsigned int deadline;                                                          // when timer goes off | 
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| 9 | unsigned int timer;                                                                     // up counter to deadline | 
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| 10 | }; // Potato | 
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| 11 |  | 
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| 12 | void reset( Potato & potato, unsigned int maxTicks = 10 ); | 
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| 13 | void ?{}( Potato & potato, PRNG & prng, unsigned int maxTicks = 10 ); | 
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| 14 |  | 
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| 15 | void ?{}( Potato & potato, PRNG & prng, unsigned int maxTicks ) with(potato) { | 
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| 16 | &potato.prng = &prng; | 
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| 17 | reset( potato, maxTicks ); | 
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| 18 | } // Potato | 
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| 19 |  | 
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| 20 | coroutine Player { | 
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| 21 | PRNG & prng; | 
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| 22 | int id;                                                                                         // player identity | 
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| 23 | Potato & potato;                                                                        // potato being tossed | 
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| 24 | Player * partner[2];                                                            // left and right player | 
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| 25 | }; // Player | 
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| 26 |  | 
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| 27 | void ?{}( Player & player, PRNG & prng, unsigned int id, Potato & potato ) { | 
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| 28 | &player.prng = &prng; | 
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| 29 | player.id = id; | 
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| 30 | &player.potato = &potato; | 
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| 31 | } // Player | 
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| 32 |  | 
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| 33 | Player & umpire; | 
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| 34 |  | 
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| 35 | ExceptionDecl( Explode ); | 
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| 36 | ExceptionDecl( Terminate, Player * victim; ); | 
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| 37 | ExceptionDecl( Election ); | 
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| 38 | ExceptionDecl( cmd_error ); // convert(...) throws out_of_range or invalid_argument | 
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| 39 |  | 
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| 40 | void reset( Potato & potato, unsigned int maxTicks ) with(potato) { | 
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| 41 | if ( maxTicks < 2 ) abort( "Hot Potato initialized with less than 2 ticks" ); // optional | 
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| 42 | deadline = prng( prng, 1, maxTicks ); | 
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| 43 | timer = 0; | 
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| 44 | sout | "  POTATO goes off after " | deadline | " tick" | nosep | (deadline > 1 ? "s" : ""); | 
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| 45 | } // reset | 
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| 46 |  | 
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| 47 | void countdown( Potato & potato ) with(potato) { | 
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| 48 | timer += 1; | 
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| 49 | if ( timer == deadline ) throwResume ExceptionInst( Explode ); | 
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| 50 | } // countdown | 
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| 51 |  | 
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| 52 | static unsigned int rightOf( unsigned int me, unsigned int total ) { | 
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| 53 | return ( me + 1 ) % total; | 
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| 54 | } // rightOf | 
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| 55 |  | 
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| 56 | static unsigned int leftOf( unsigned int me, unsigned int total ) { | 
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| 57 | return ( me + total - 1) % total; | 
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| 58 | } // leftOf | 
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| 59 |  | 
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| 60 | enum { LEFT = 0, RIGHT = 1 }; | 
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| 61 |  | 
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| 62 | static void vote( Player & player, Election & election ) { // cause partner to vote | 
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| 63 | resumeAt( player, election ); | 
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| 64 | resume( player ); | 
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| 65 | } // vote | 
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| 66 |  | 
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| 67 | void init( Player & player, Player & lp, Player & rp ) with(player) { // supply partners | 
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| 68 | partner[LEFT] = &lp; | 
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| 69 | partner[RIGHT] = &rp; | 
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| 70 | resume( player );                                                                       // establish main as starter for termination | 
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| 71 | } // init | 
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| 72 |  | 
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| 73 | int getId( Player & player ) {                                                  // player id | 
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| 74 | return player.id; | 
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| 75 | } // getId | 
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| 76 |  | 
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| 77 | void main( Player & player ) with(player) { | 
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| 78 | suspend;                                                                                        // return immediately after establishing starter | 
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| 79 | try { | 
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| 80 | for ( ;; ) { | 
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| 81 | poll();                                                                         // check for non-local exceptions before proceeding | 
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| 82 |  | 
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| 83 | if ( partner[LEFT] == &player ) {                       // stop when only one player | 
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| 84 | sout | id | " wins the Match!"; | 
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| 85 | return; | 
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| 86 | } // exit | 
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| 87 |  | 
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| 88 | countdown( potato );                                            // player is eliminated if countdown() returned true | 
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| 89 |  | 
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| 90 | size_t side = prng( prng, 2 ); | 
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| 91 | sout | id | " -> " | nonl; | 
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| 92 | resume( *partner[ side ] );                                     // random toss left/right | 
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| 93 | } // for | 
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| 94 | } catchResume( Terminate * v ) { | 
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| 95 | v->victim->partner[LEFT]->partner[RIGHT] = v->victim->partner[RIGHT]; // unlink node | 
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| 96 | v->victim->partner[RIGHT]->partner[LEFT] = v->victim->partner[LEFT]; | 
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| 97 | delete( v->victim ); | 
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| 98 | reset( potato ); | 
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| 99 | sout | "U " | nonl;                                                             // start new game | 
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| 100 | flush( sout ); | 
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| 101 | } catchResume( Election * election ) { | 
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| 102 | sout | "election"; | 
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| 103 | sout | " -> " | id | nonl; | 
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| 104 | if ( id > getId( umpire ) ) &umpire = &player;  // set umpire to highest id so far | 
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| 105 | vote( *partner[RIGHT], *election ); | 
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| 106 | } catchResume ( Explode * ) { | 
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| 107 | sout | id | " is eliminated"; | 
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| 108 | if ( &player == &umpire ) { | 
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| 109 | id = -1;                                                                        // remove from election | 
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| 110 | vote( *partner[RIGHT], ExceptionInst( Election ) );     // start election | 
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| 111 | try { poll(); } catchResume( Election * election ) {} // handle end of election | 
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| 112 | sout | " : umpire " | getId( umpire ); | 
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| 113 | } // if | 
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| 114 | resumeAt( umpire, ExceptionInst( Terminate, &player ) ); | 
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| 115 | resume( umpire );                                                               // resume umpire to terminate this player | 
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| 116 | assert( false );                                                                // no return | 
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| 117 | } // try | 
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| 118 | } // main | 
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| 119 |  | 
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| 120 |  | 
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| 121 | int main( int argc, char * argv[] ) { | 
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| 122 | enum { | 
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| 123 | MinNoPlayers = 2,                                                               // minimum players in the game | 
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| 124 | MaxNoPlayers = 10,                                                              // maximum players in the game | 
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| 125 | DefaultGames = 5,                                                               // default games to play | 
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| 126 | }; | 
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| 127 | intmax_t numGames = DefaultGames;                                       // games to play | 
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| 128 | intmax_t numPlayers = 0;                                                        // players for a particular game | 
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| 129 | intmax_t seed = 42;                                                                     // random-number seed | 
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| 130 | bool playersSet = false; | 
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| 131 | char * nosummary = getenv( "NOSUMMARY" );                       // print extra output | 
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| 132 |  | 
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| 133 | try { | 
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| 134 | choose ( argc ) { | 
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| 135 | case 4: | 
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| 136 | if ( strcmp( argv[3], "d" ) != 0 ) {            // default ? | 
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| 137 | seed = convert( argv[3] ); if ( seed < 1 ) throw ExceptionInst( cmd_error ); // invalid ? | 
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| 138 | } // if | 
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| 139 | fallthrough; | 
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| 140 | case 3: | 
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| 141 | if ( strcmp( argv[2], "d" ) != 0 ) {            // default ? | 
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| 142 | numPlayers = convert( argv[2] ); if ( numPlayers < 2 ) throw ExceptionInst( cmd_error ); // invalid ? | 
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| 143 | playersSet = true; | 
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| 144 | } // if | 
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| 145 | fallthrough; | 
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| 146 | case 2: | 
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| 147 | if ( strcmp( argv[1], "d" ) != 0 ) {            // default ? | 
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| 148 | numGames = convert( argv[1] ); if ( numGames < 0 ) throw ExceptionInst( cmd_error ); // invalid ? | 
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| 149 | } // if | 
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| 150 | fallthrough; | 
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| 151 | case 1: ;                                                                             // defaults | 
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| 152 | default:                                                                              // too many arguments | 
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| 153 | throw ExceptionInst( cmd_error ); | 
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| 154 | } // choose | 
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| 155 | } catch( exception_t * ) {                                                      // catch any | 
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| 156 | exit | "Usage: " | argv[0] | 
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| 157 | | " [ games (>=0) | 'd' (default " | DefaultGames | 
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| 158 | | ") [ players (>=2) | 'd' (random " | MinNoPlayers | "-" | MaxNoPlayers | 
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| 159 | | ") [ seed (>0) | 'd' (random) ] ] ]"; | 
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| 160 | } // try | 
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| 161 | sout | numGames | numPlayers | seed; | 
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| 162 |  | 
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| 163 | PRNG mprng, hprng, pprng; | 
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| 164 | if ( seed != 0 ) {                                                                      // specified on command line ? | 
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| 165 | set_seed( mprng, seed );  set_seed( hprng, seed );  set_seed( pprng, seed ); | 
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| 166 | } // if | 
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| 167 |  | 
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| 168 | for ( game; 1 ~= numGames ) { | 
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| 169 | if ( ! playersSet ) numPlayers = prng( mprng, MinNoPlayers, MaxNoPlayers ); | 
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| 170 | sout | numPlayers | " players in the game"; | 
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| 171 | { | 
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| 172 | Potato potato{ hprng };                                         // hot potato to be tossed | 
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| 173 | Player * players[numPlayers]; | 
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| 174 |  | 
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| 175 | for ( unsigned int i = 0; i < (unsigned int)numPlayers; i += 1 ) { // start the players | 
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| 176 | players[i] = malloc(); | 
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| 177 | ?{}( *players[i], pprng, i, potato ); | 
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| 178 | } // for | 
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| 179 |  | 
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| 180 | // Do not swap player[0] with itself. | 
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| 181 | unsigned int rposn = prng( mprng, 1, numPlayers - 1 ); // swap random position with 0 | 
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| 182 | swap( players[0], players[rposn] ); | 
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| 183 |  | 
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| 184 | // Tell each player its partner. | 
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| 185 | for ( unsigned int i = 0; i < (unsigned int)numPlayers; i += 1 ) { | 
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| 186 | init( *players[i], *players[leftOf(i, numPlayers)], *players[rightOf(i, numPlayers)] ); | 
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| 187 | } // for | 
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| 188 |  | 
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| 189 | &umpire = players[rposn];                                       // designate umpire and start game | 
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| 190 | sout | "U " | nonl; | 
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| 191 | resume( *players[rposn] ); | 
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| 192 | delete( &umpire ); | 
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| 193 | } | 
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| 194 | if ( game < (unsigned int)numGames ) sout | nl | nl; // whitespace between games | 
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| 195 | } // for | 
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| 196 | } // main | 
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| 197 |  | 
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| 198 | // Local Variables: // | 
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| 199 | // compile-command: "make hotpotato" // | 
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| 200 | // End: // | 
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