BEGIN "NTONIC"
REQUIRE "DDSUB.SAI[GRA,HPM]" SOURCE_FILE;
REQUIRE "PRANDR.SAI[BIG,HPM]" SOURCE_FILE;
DEFINE NEL=4, N=4, NOPEN=4;
INTEGER DONE,FOO,I,J,K,L;
STRING S; BOOLEAN MERGE,PASS;
INTEGER ARRAY WIRE[0:N-1,0:NEL-1],STATE[0:N-1,0:NEL-1],NSET[0:NEL-1];
INTEGER ARRAY NEXT,PERM,OUTPUT,INPUTMAP[0:N*NOPEN-1];

PROCEDURE FOLLOW;
   BEGIN
   INTEGER I,J,K,L;
   DONE←0;
   WHILE DONE<NEL DO FOR I←0 STEP 1 UNTIL NEL-1 DO IF NSET[I]=N THEN
      BEGIN
      FOR J←1 STEP 1 UNTIL N-1 DO FOR K←0 STEP 1 UNTIL J-1 DO
         IF STATE[J,I]<STATE[K,I] THEN STATE[J,I]↔STATE[K,I];
      FOR J←0 STEP 1 UNTIL N-1 DO
         BEGIN
         K←WIRE[J,I];
         IF K≥0 THEN
            BEGIN
            L←NSET[K];
            NSET[K]←L+1;
            STATE[L,K]←STATE[J,I];
            END
         ELSE
            OUTPUT[-1-K]←STATE[J,I];
         END;
      NSET[I]←-N;
      DONE←DONE+1;
      END;
   END;

PROCEDURE DRAW;
   BEGIN
   REAL ARRAY X,Y[0:NEL-1];
   INTEGER I,J,K;

   PROCEDURE SET(INTEGER L; REAL XV,YV);
      BEGIN X[L]←XV; Y[L]←YV; END;

   SET(0,1,1);
   SET(1,1,2);
   SET(2,1,3);
   SET(3,1,4); 
   DDINIT;
   SCREEN(-1,-.1,6,6);
   DRKEN; RECTAN(-100,-100,100,100); LITEN;
   FOR I←0 STEP 1 UNTIL NEL-1 DO RECTAN(X[I]-.1,Y[I]-.2,X[I]+.2,Y[I]+.2);
   FOR I←0 STEP 1 UNTIL N*NOPEN-1 DO
      LINE(0,I*5/15,X[INPUTMAP[I]],Y[INPUTMAP[I]]);
   FOR I←0 STEP 1 UNTIL NEL-1 DO
   FOR J←0 STEP 1 UNTIL N-1 DO
      BEGIN REAL FX,FY;
      FX←X[I]+.2; FY←Y[I]+(J/(N-1)-.5)*.4;
      IF WIRE[J,I]<0 THEN LINE(FX,FY,4,(-1-WIRE[J,I])*5/15)
         ELSE LINE(FX,FY,X[WIRE[J,I]],Y[WIRE[J,I]]);
      END;
   FOR I←1,2,3 DO DPYUP('36);
   SHOW('36);
   END;
PROCEDURE M4WAY(INTEGER FIRST; INTEGER ARRAY NEXT);
   BEGIN
   INTEGER I,J;
   FOR I←0 STEP 1 UNTIL N-1 DO FOR J←0 STEP 1 UNTIL N-1 DO
      WIRE[J,I+FIRST]←NEXT[J+4*I];
   END;

FOR J←0 STEP 1 UNTIL 15 DO INPUTMAP[J]←J MOD 4;
OUTSTR("INPUTMAP ");
FOR I←0 STEP 1 UNTIL N*NOPEN-1 DO OUTSTR(CVS(INPUTMAP[I])&" "); OUTSTR('15&'12);

FOR I←0 STEP 1 UNTIL N*NOPEN-1 DO NEXT[I]←-1-I;
M4WAY(0,NEXT);
DRAW;
OUTSTR('12&"WIRES "&'15&'12);
FOR J←0 STEP 1 UNTIL N-1 DO
   BEGIN
   FOR I←0 STEP 1 UNTIL NEL-1 DO OUTSTR(CVS(WIRE[J,I])&" ");
   OUTSTR('15&'12);
   END;
OUTSTR('15&'12&'12);

   BEGIN
   INTEGER ARRAY CNTR[1:N*NOPEN];
   INTEGER ARRAY CHECK[0:N*NOPEN,0:N*NOPEN];
   FOR I←1 STEP 1 UNTIL N*NOPEN DO CNTR[I]←(N*NOPEN-I)%NOPEN;
   MERGE←TRUE;
   DO
      BEGIN
      K←-1;
      FOR I←N-1 STEP -1 UNTIL 0 DO FOR J←1 STEP 1 UNTIL N*NOPEN DO
         IF CNTR[J]=I THEN PERM[K←K+1]←J;
      FOR I←0 STEP 1 UNTIL NEL-1 DO NSET[I]←0;
      FOR I←0 STEP 1 UNTIL N*NOPEN-1 DO
         BEGIN
         K←INPUTMAP[I];
         L←NSET[K];
         NSET[K]←L+1;
         STATE[L,K]←PERM[I];
         END;
      FOLLOW;
      PASS←FALSE;
      FOR K←0 STEP 1 UNTIL N*NOPEN-1 DO
         BEGIN
         L←0; WHILE CHECK[K,L]≠0∧CHECK[K,L]<OUTPUT[K] DO L←L+1;
         IF CHECK[K,L]≠OUTPUT[K] THEN
            BEGIN
            WHILE OUTPUT[K]≠0 DO
               BEGIN
               CHECK[K,L]↔OUTPUT[K];
               L←L+1;
               END;
            PASS←TRUE;
            END;
         END;
      IF PASS THEN
         BEGIN
         DRKEN; RECTAN(4.01,-100,100,100); LITEN;
         FOR K←0 STEP 1 UNTIL N*NOPEN-1 DO
            BEGIN
            TXTPOS(4.01,(N*NOPEN-1-K-.5)*5/15+.2,.1,.2);
            L←0; WHILE CHECK[K,L]≠0 DO TEXT('77+CHECK[K,(L←L+1)-1]);
            END;
         DPYUP('36);
         END;
      PWITHR(CNTR,N*NOPEN,MERGE);
      END UNTIL MERGE;
   END;

END;