Mathematica 24点程序！

cjilyy

f[x1_, s1_, x2_, s2_, x3_, s3_, x4_] :=
% v4 E3 M( v0 ~# z( J$ D Module[{result, i},
  r8 R+ F; X: a3 f" t- ~3 G  result = {HoldForm[(x1~s1~x2)~s2~(x3~s3~x4)],
    HoldForm[x1~s1~(x2~s2~x3~s3~x4)],
    HoldForm[x1~s1~x2~s2~(x3~s3~x4)],
    HoldForm[(x1~s1~x2~s2~x3)~s3~x4],
    HoldForm[x1~s1~(x2~s2~x3)~s3~x4],
    HoldForm[(x1~s1~(x2~s2~x3))~s3~x4],
& Z) A9 H( [* W: W3 l& J    HoldForm[x1~s1~(x2~s2~(x3~s3~x4))]};
  result = Union[result];
9 W( t1 G! V1 r6 U5 M2 _  For[i = 1, i <= Length[result], i++,
" V, h' ?+ M% T& ]   If[ReleaseHold[result[[i]]] == 24, Print[result[[i]], "=24"];
; a. k. X: R/ Q% i1 s3 q: ^- M) H, f     (*Print[TreeForm[result[[i]],DirectedEdges->True]]*);];];]

5 T9 s* Y, ]% }% s9 o; y5 xfs[x1_, x2_, x3_, x4_] :=
Module[{result, s, sym, num, i, j}, Off[Divide::infy];
$ h/ W$ x9 R% {* ?9 V# Y  Off[Part::partw];
  Off[Divide::indet];
/ e( {8 ]& S0 Z! n% L. }# s- U  s = {Plus, Subtract, Times, Divide};
  sym = Flatten[
. r( u6 Z% d: D) p1 k& ~    Table[{s[[i]], s[[j]], s[[k]]}, {i, 4}, {j, 4}, {k, 4}], 2];
  sym = Union[sym];
  num = Permutations[{x1, x2, x3, x4}];
  |9 D5 C, u1 f8 ^  Do[f[num[[i, 1]], sym[[j, 1]], num[[i, 2]], sym[[j, 2]],
. B: p5 P: p0 G) @( }! }  G    num[[i, 3]], sym[[j, 3]], num[[i, 4]]], {i, Length[num]}, {j,
+ ?' |5 r+ i: h8 F    Length[sym]}]]
# p7 @0 ?7 e- ?1 r
& ?' |, c; u1 F# b# d0 v, }fs[3, 3, 8, 8]