Mathematica 24点程序！

cjilyy

f[x1_, s1_, x2_, s2_, x3_, s3_, x4_] :=
Module[{result, i},
  result = {HoldForm[(x1~s1~x2)~s2~(x3~s3~x4)],
    HoldForm[x1~s1~(x2~s2~x3~s3~x4)],
4 N3 J- p2 L& B& z    HoldForm[x1~s1~x2~s2~(x3~s3~x4)],
; H& q; o, e6 h3 x; H# j    HoldForm[(x1~s1~x2~s2~x3)~s3~x4],
0 n) t' Y5 c/ Z8 W    HoldForm[x1~s1~(x2~s2~x3)~s3~x4],
    HoldForm[(x1~s1~(x2~s2~x3))~s3~x4],
    HoldForm[x1~s1~(x2~s2~(x3~s3~x4))]};
) a3 J& z( N$ S$ s0 S2 J  result = Union[result];
  For[i = 1, i <= Length[result], i++,
   If[ReleaseHold[result[[i]]] == 24, Print[result[[i]], "=24"];
     (*Print[TreeForm[result[[i]],DirectedEdges->True]]*);];];]
3 o( V( z! P% q) N0 Y$ I7 M; s" e
, s0 h0 J8 e4 y: @2 y* z6 F- Ufs[x1_, x2_, x3_, x4_] :=
- e+ H6 M' o  V6 W7 v6 f Module[{result, s, sym, num, i, j}, Off[Divide::infy];
2 X5 D; C1 t! T- q; r2 Z7 S  Off[Part::partw];
  Off[Divide::indet];
7 M# U2 A9 U1 R1 I0 p' i. u, @  s = {Plus, Subtract, Times, Divide};
2 [  t* g& q; d. M" a; s9 J  sym = Flatten[
    Table[{s[[i]], s[[j]], s[[k]]}, {i, 4}, {j, 4}, {k, 4}], 2];
  sym = Union[sym];
  num = Permutations[{x1, x2, x3, x4}];
2 |% n8 }' C! C7 r  Do[f[num[[i, 1]], sym[[j, 1]], num[[i, 2]], sym[[j, 2]],
    num[[i, 3]], sym[[j, 3]], num[[i, 4]]], {i, Length[num]}, {j,
- O  ]: w! Z0 ]' X+ R3 S1 u    Length[sym]}]]

6 J( B  X" s7 m* _! j! Sfs[3, 3, 8, 8]