* set N for NxN size chess board * solves how to place N queens on NxN board with none attacking any other * Program written by Viktors Berstis N = 8 NM1 = N - 1; NP1 = N + 1; NSZ = N * NP1 &ANCHOR = 1 DEFINE('SOLVE(B)I') TEST = BREAK('Q') 'Q' (ARBNO(LEN(N ) '-') LEN(N ) 'Q' + | ARBNO(LEN(NP1) '-') LEN(NP1) 'Q' + | ARBNO(LEN(NM1) '-') LEN(NM1) 'Q') P = LEN(NM1) . X LEN(1); L = 'Q' DUPL('-',NM1) ' ' SOLVE() :(END) SOLVE EQ(SIZE(B),NSZ) :S(PRINT) B = L B LOOP I = LT(I,N) I + 1 :F(RETURN) B TEST :S(NEXT) SOLVE(B) NEXT B P = '-' X :(LOOP) PRINT SOLUTION = SOLUTION + 1 OUTPUT = 'Solution number ' SOLUTION ' is:' PRTLOOP B LEN(NP1) . OUTPUT = :S(PRTLOOP)F(RETURN) END