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<title>24點（電腦幫你算） 算24的頁面 </title>
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<font style="font-size: 15pt" face="黑體" color="#008000">24點（電腦幫你算）</font><font style="font-size: 15pt" face="楷體_GB2312" color="#008000"><br>
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計算24點(加、減、乘、除、括號)<br><br>
<br><br>
玩法：從撲克中任意抽出四張（數字表示為1－13），用加、減、乘、除的方法使結果成為24，每張牌只能用一次。
一副牌（52張）中，任意抽取4張可有1820種不同組合，其中有458個牌組算不出24點。現在再和別人玩這個游戲，不怕了吧？Let's play cards!<br><br><br>
<form>
請輸入四個數字(1-13)：<br><br>
<input type="text" name="fa" size="2">
<input type="text" name="fb" size="2">
<input type="text" name="fc" size="2">
<input type="text" name="fd" size="2">
<br><br><input type="button" name="btn" onclick="javascript:funCount()" value=" 計算 ">
</form>
<br><script language="JavaScript">
function log(str)
{
document.write("<br>"+str);
}
//生成計算表達式
function genExpress(exp,a,b,c,d,m1,m2,m3)
{
var exp=exp.replace("a",a);
exp=exp.replace("b",b);
exp=exp.replace("c",c);
exp=exp.replace("d",d);
exp=exp.replace("m1",m1);
exp=exp.replace("m2",m2);
exp=exp.replace("m3",m3);
return exp;
}
var answer = new Array();//正確答案的表達式
var counter = 0;//答案的個數
//測試表達式是否正確
function test(expn,a,b,c,d,m1,m2,m3)
{
var exp;
var ret;
exp = genExpress(expn,a,b,c,d,m1,m2,m3);//生成計算表達式
eval("ret = "+exp);
if ( Math.abs(ret - 24) < 0.1 )
{
exp = exp.replace(";","");
exp = replaceAll(exp,"*","×");
exp = replaceAll(exp, "/","÷");
var have = false;
for ( var i=0; i<counter; i++)
{
if ( exp == answer[i] )
{
have = true;
break;
}
}
if ( !have )
{
answer[counter] = exp;
counter++;
log("<font color=red><b>"+counter+": "+exp+"</b></font>");
}
}
}
function replaceAll (streng, soeg, erstat)
{
var st = streng;
if (soeg.length == 0)
return st;
var idx = st.indexOf(soeg);
while (idx >= 0)
{
st = st.substring(0,idx) + erstat + st.substr(idx+soeg.length);
idx = st.indexOf(soeg);
}
return st;
}
var n = new Array();//四個數字
//接收四個輸入框的數字，調用主程序
function funCount()
{
n[0] = document.forms[0].fa.value;
n[1] = document.forms[0].fb.value;
n[2] = document.forms[0].fc.value;
n[3] = document.forms[0].fd.value;
if ( n[0] > 0 && n[1] > 0 && n[2] > 0 && n[3] > 0 && n[0] < 14 && n[1] < 14 && n[2] < 14 && n[3] < 14 )
{
log("<font size=5><b>"+n[0]+", "+n[1]+", "+n[2]+", "+n[3]+"的24點答案：</b></font><br>");
log("<input type='button' onclick='history.back(-1);' value=' 再來一次 '><br>");
funMain();
if ( counter == 0 )
{
log("沒有答案！");
}
}
else
{
alert("輸入錯誤！");
}
}
//主程序
function funMain()
{
var m = new Array();
//四種運算符
m[0] = "+";
m[1] = "-";
m[2] = "*";
m[3] = "/";
//11種表達式
var exp1 = "a m1 b m2 c m3 d;";
var exp2 = "(a m1 b) m2 c m3 d;";
var exp3 = "(a m1 b m2 c) m3 d;";
var exp4 = "((a m1 b) m2 c) m3 d;";
var exp5 = "(a m1 (b m2 c)) m3 d;";
var exp6 = "a m1 (b m2 c) m3 d;";
var exp7 = "a m1 (b m2 c m3 d);";
var exp8 = "a m1 ((b m2 c) m3 d);";
var exp9 = "a m1 (b m2 (c m3 d));";
var exp10 = "a m1 b m2(c m3 d);";
var exp11 = "(a m1 b) m2 (c m3 d);";
var a,b,c,d;//四個數字
var m1,m2,m3;//三個運算符
for (var i=0;i<4;i++)
{
a = n[i];
for (var j=0;j<4;j++)
{
if ( i == j ) continue;//從未選的三個數字中選擇一個數字
b = n[j];
for (var x=0;x<4;x++)
{
if ( x == j || x == i ) continue;//從未選的兩個數字中選擇一個數字
c = n[x];
for (var y=0;y<4;y++)
{
if ( y == x || y == j || y == i ) continue;//從未選的一個數字中選擇一個數字
d = n[y];
for (var ta=0;ta<4;ta++)
{
m1 = m[ta];
for (var tb=0;tb<4;tb++)
{
m2 = m[tb];
for (var tc=0;tc<4;tc++)
{
m3 = m[tc];
for (var k=1;k<12;k++)
{
eval("test(exp"+k+",a,b,c,d,m1,m2,m3);");
}
}
}
}
}
}
}
}
}
</script>
