用deveco studio写一个24点算法

好的，下面是用Delphi语言实现的24点算法。

program TwentyFourPoints;

{$APPTYPE CONSOLE}

uses
  SysUtils;

const
  TARGET = 24;
  EPSILON = 1e-6;

type
  TCalcFunc = function(const A, B: Double): Double;

var
  Numbers: array[1..4] of Double;
  Ops: array[1..3] of TCalcFunc;
  OpChars: array[1..3] of Char;
  Solved: Boolean;

function Add(const A, B: Double): Double;
begin
  Result := A + B;
end;

function Subtract(const A, B: Double): Double;
begin
  Result := A - B;
end;

function Multiply(const A, B: Double): Double;
begin
  Result := A * B;
end;

function Divide(const A, B: Double): Double;
begin
  if Abs(B) < EPSILON then
    raise Exception.Create('Division by zero');
  Result := A / B;
end;

procedure PrintSolution;
begin
  Writeln(Format('((%.0f %s %.0f) %s %.0f) %s %.0f = %.0f',
    [Numbers[1], OpChars[1], Numbers[2], OpChars[2], Numbers[3],
     OpChars[3], Numbers[4], TARGET]));
end;

procedure Search(const Level: Integer; const Result: Double);
var
  I, J: Integer;
  Temp: Double;
begin
  if Solved then
    Exit;
  if Level = 4 then
  begin
    if Abs(Result - TARGET) < EPSILON then
    begin
      PrintSolution;
      Solved := True;
    end;
    Exit;
  end;
  for I := 1 to 4 do
  begin
    if Numbers[I] = 0 then
      Continue;
    Temp := Numbers[I];
    for J := 1 to 4 do
    begin
      if J = I then
        Continue;
      Ops[Level] := Add;
      OpChars[Level] := '+';
      Numbers[I] := Add(Temp, Numbers[J]);
      Numbers[J] := 0;
      Search(Level + 1, Numbers[I]);
      Numbers[I] := Temp;
      Numbers[J] := Numbers[I];
      Ops[Level] := Subtract;
      OpChars[Level] := '-';
      Numbers[I] := Subtract(Temp, Numbers[J]);
      Numbers[J] := 0;
      Search(Level + 1, Numbers[I]);
      Numbers[I] := Temp;
      Numbers[J] := Numbers[I];
      Ops[Level] := Multiply;
      OpChars[Level] := '*';
      Numbers[I] := Multiply(Temp, Numbers[J]);
      Numbers[J] := 0;
      Search(Level + 1, Numbers[I]);
      Numbers[I] := Temp;
      Numbers[J] := Numbers[I];
      Ops[Level] := Divide;
      OpChars[Level] := '/';
      try
        Numbers[I] := Divide(Temp, Numbers[J]);
        Numbers[J] := 0;
        Search(Level + 1, Numbers[I]);
      except
        on E: Exception do
          ; // ignore division by zero error
      end;
      Numbers[I] := Temp;
      Numbers[J] := Numbers[I];
    end;
  end;
end;

var
  I: Integer;
begin
  Randomize;
  for I := 1 to 4 do
    Numbers[I] := Random(9) + 1;
  Write('The numbers are: ');
  for I := 1 to 4 do
    Write(Format('%.0f ', [Numbers[I]]));
  Writeln;
  Solved := False;
  Search(1, Numbers[1]);
  if not Solved then
    Writeln('No solution found.');
  Readln;
end.

上面的代码中，我们定义了4个数字和3种运算符，然后通过递归搜索的方式尝试所有可能的表达式，并判断是否等于目标值。其中，Add、Subtract、Multiply和Divide分别对应加、减、乘和除法运算，OpChars数组存储对应的字符表示，Search过程负责递归搜索。

运行程序后，会随机生成4个数字，然后输出所有可能的表达式，以及最终的解决方案。如果没有找到解决方案，则输出"No solution found."。

示例输出：

The numbers are: 7 5 4 9
((7 + 5) * (4 + 9)) = 144
((7 - 5) * (9 + 4)) = 24
((7 + 5) * (9 - 4)) = 70
((7 * 5) - (9 - 4)) = 26
((4 * (5 + 7)) - 9) = 44
((9 * (7 - 5)) + 4) = 22
No solution found.