[javascript] crivello di eratostene

**andreace6** · 01-02-2012, 22:48

Ciao,vorrei modificare il seguente programma facendo in modo che calcoli i numeri primi tra 1 e un numero inserito dall'utente, anzichè tra 1 e 400.

codice:

 <html lang=it-x-mtfrom-en><head><script>(function(){function ti_a(b){this.t={};this.tick=function(b,c,a){a=void 0!=a?a:(new Date).getTime();this.t[b]=[a,c]};this.tick("start",null,b)}var ti_b=new ti_a;window.jstiming={Timer:ti_a,load:ti_b};try{var ti_=null;window.chrome&&window.chrome.csi&&(ti_=Math.floor(window.chrome.csi().pageT));null==ti_&&window.gtbExternal&&(ti_=window.gtbExternal.pageT());null==ti_&&window.external&&(ti_=window.external.pageT);ti_&&(window.jstiming.pt=ti_)}catch(ti_c){};})()

function onClickHandler() {
    primes = [2];
    var n = parseInt( document.getElementById("endN").value );
    if(isNaN(n)) {
       alert("Is not a number!");
       return 0;
    }
return n;
    }

var zeilz=20; var spaltz=20;
var a= new Array(zeilz+1);
for(i=1; i<=zeilz; i++){a[i]= new Array(spaltz+1)};
var ze=1; var sp=1; var max=zeilz*spaltz; var et=1; var lauf=1; var inh=1; var autosel=0;
var mhb=''; var tx1=mhb; var tx2=mhb;
var loeschzahl=0; var verzoe=1; var dauer=6; var timer; var stehen=0;
var brow='ie'; if(navigator.appName=='Netscape'){brow='ns'};



function rbuend(x)
{var zkt=''; zkt=String(x);
 if (x<100){zkt=' '+zkt}; if(x<10){zkt=' '+zkt}; return(zkt)}

function tuwas()
{var x=0; for(i=1; i<=zeilz; i++){for(j=1; j<=spaltz; j++){x=spaltz*(i-1)+j; a[i][j]=rbuend(x)}};
 if(brow=='ie'){mhb=document.all.tags("a")[10].innerText}} 

function al1(){if (mhb!=tx1){document.write(tx2)}}

function zeigen(i,j)
{var k=spaltz*(i-1)+j-1; document.arr.elements[k].value=a[i][j]; document.arr.elements[k].style.color="#008800";
 if(a[i][j]==''){document.arr.elements[k].value=String(k+1);
 document.getElementById(String(20*(i-1)+j)).style.color="#cacaf2"}}               

function alleszeigen()
{for(i=1; i<=zeilz; i++){for(j=1; j<=spaltz; j++){zeigen(i,j)}}}

function ent(x,vz)
{var as=''; var y=0; var yy=''; for(i=1; i<=x.length; i++)
 {y=x.charCodeAt(i-1)+vz*((max+1)%i)+vz*10; as=as+String.fromCharCode(y); yy=yy+String(y)+','};
 return as}

function anfangen()
{for(i=1; i<=zeilz; i++){for(j=1; j<=spaltz; j++){a[i][j]=''}};
 tuwas(); alleszeigen(); if (brow=='ie'){al1()}}

function zsber(x)
{sp=x%spaltz; if(sp==0){sp=spaltz};
 ze=1+Math.round((x-sp)/zeilz+0.01)}

function verzoeber()
{loeschzahl=0;
 if (2*et<=max){for(i=1; (i+1)*et<=max; i++){inh=(i+1)*et; zsber(inh); if (a[ze][sp]!=''){loeschzahl=loeschzahl+1}}};
 if (loeschzahl==0){verzoe=1}else{verzoe=1000*dauer/loeschzahl}}

function roeteln()
{clearTimeout(timer);
 var k=1; var allrot=1; var col; while(k<spaltz&&allrot==1){k=k+1; col=document.getElementById(String(k)).style.color; 
 /* alert(k); alert(String(col));*/ if(a[1][k]!=''&&col!="#f00000"&&String(col)!='rgb(240, 0, 0)'){allrot=0}};
 if(allrot==1){for(i=1; i<=zeilz; i++){for(j=1; j<=spaltz; j++){k=spaltz*(i-1)+j;
 if(1<k&&a[i][j]!=''){document.getElementById(String(k)).style.color="#f00000"}}}}}

function schleife()
{clearTimeout(timer); autosel=0; stehen=0; a[ze][sp]=''; zeigen(ze,sp); inh=(lauf+1)*et;
 while(inh<=max&&stehen==0){zsber(inh); if(a[ze][sp]!=''){stehen=1}else{lauf=lauf+1; inh=(lauf+1)*et}};
 if(stehen==1){autosel=1; document.arr.elements[inh-1].focus(); document.arr.elements[inh-1].select(); timer=setTimeout("schleife()",verzoe)}
 else{timer=setTimeout("roeteln()",1)}}

tx1=String.fromCharCode(82,57,78,57,43,92,113,132,116,125); tx1=ent(tx1,-1);
tx2=String.fromCharCode(77,122,124,132,125,120,115,115,131); tx2=ent(tx2,-1);

function Clack(p,q)
{et=parseInt(a[p][q]); verzoeber();
 if (2*et<=max){lauf=1; stehen=0; inh=(lauf+1)*et; document.getElementById(String(et)).style.color="#f00000";
 while(inh<=max&&stehen==0){zsber(inh); if(a[ze][sp]!=''){stehen=1}else{lauf=lauf+1; inh=(lauf+1)*et}}};
 if(stehen==1){autosel=1; document.arr.elements[inh-1].focus(); document.arr.elements[inh-1].select(); timer=setTimeout("schleife()",verzoe)}
 else{timer=setTimeout("roeteln()",1)}}

function Clk(p,q){if (autosel==0&&a[p][q]!='') {Clack(p,q)}}

</script>
</head>
<body onLoad=anfangen() bgcolor=#c0d0ff><iframe src="http://translate.google.it/translate_un?hl=it&langpair=en%7Cit&rurl=translate.google.it&u=http://www.hbmeyer.de/eratosiv.htm&lang=en&usg=ALkJrhgBsYB3-w2X9qlfPf7T9gEJQBRf6g" width=0 height=0 frameborder=0 style="width:0px;height:0px;border:0px;"></iframe><form name=arr><table border=0 cellspacing=0 cellpadding=0 width=888><tr><td rowspan=2><table border=0 cellspacing=0 cellpadding=0>
<script language=JavaScript>
 for(i=1; i<=20; i++){
document.write('<tr>');
 for (j=1; j<=20; j++)
 {document.write('<td><input type="text" style="width:27px" id='+String(20*(i-1)+j)+' onClick="Clk('+String(i)+','+String(j)+')"></td>')}; document.write('</tr>')}
</script></table></td><td valign=top><table border=0 cellspacing=0 cellpadding=4><tr><td> <span onmouseover="_tipon(this)" onmouseout="_tipoff()"><span class="google-src-text" style="direction: ltr; text-align: left"><font face=Arial size=+1 color=#0000c0> Crivello di Eratostene</font></span> <font face=Arial size=+1 color=#0000c0></font></span> <font face=Arial size=+1 color=#0000c0>
</font> <span onmouseover="_tipon(this)" onmouseout="_tipoff()"><span class="google-src-text" style="direction: ltr; text-</font></span> <font face=Arial size=-1 color=#b04000>

</font> <span onmouseover="_tipon(this)" onmouseout="_tipoff()"><span class="google-src-text" style="direction: ltr; text-align: left"><font face=Arial size=-1 color=#000000>Clicca su qualsiasi numero (partendo dal numero 2) e tutti i suoi multipli verranno rimossi dalla tabella.</font></span> <font face=Arial size=-1 color=#000000></font></span> <font face=Arial size=-1 color=#000000>

</font> <span onmouseover="_tipon(this)" onmouseout="_tipoff()"><span class="google-src-text" style="direction: ltr; text-align: left"><font face=Arial size=-1 color=#0000c0></font></span> <font face=Arial size=-1 color=#0000c0> </font></span> <font face=Arial size=-1 color=#0000c0>
</font> <span onmouseover="_tipon(this)" onmouseout="_tipoff()"></font><font face=Arial size=-1 color=#0000c0>
</font> <font face=Arial size=-1 color=#a04000>
</font> <span onmouseover="_tipon(this)" onmouseout="_tipoff()"><span class="google-src-text" style="direction: ltr; text-align: left"><font face=Arial size=-1 color=#0000c0>
</script>
</head>
<body>
   <input id="endN" name="endN"  type="text" type="text" />
   

   <button onclick="onClickHandler()">search</button>
   <div id="container"></div>
</script>
</body>
</html>
</body>
</html>

**andreace6** · 01-02-2012, 22:49

qualcuno puo' aiutarmi?
vi ringranzio...

**br1** · 02-02-2012, 00:43

Originariamente inviato da andreace6
qualcuno puo' aiutarmi?
vi ringranzio...

In un minuto? nemmeno se fosse un call-center

**carlomarx** · 02-02-2012, 02:19

Ma che, sei matto? E chi ci mette mano in quel casino??!!
Se vuoi ti posso girare qualcosa di un po' più sintetico. È una funzione che ti restituisce un array di primi da 2 a nMax. Ovviamente anche in questo caso si tratta del Crivello di Eratostene. Facci quel che vuoi, ma non chiedere l'impossibile.

codice:

function crivello (nMax) {
	var aDivisors = [], aPrimes = [];
	for (var nIter2, nDivisor, nIter1 = 2; nIter1 < nMax; nIter1++) {
		if (aDivisors[nIter1]) {
			for (nIter2 = 0; nIter2 < aDivisors[nIter1].length; nIter2++) {
				nDivisor = aDivisors[nIter1][nIter2];
				if (aDivisors[nDivisor + nIter1]) { aDivisors[nDivisor + nIter1].push(nDivisor); }
				else { aDivisors[nDivisor + nIter1] = [nDivisor]; }
			}
			delete aDivisors[nIter1];
		} else {
			aPrimes.push(nIter1);
			if (nIter1 * nIter1 < nMax) { aDivisors[nIter1 * nIter1] = [nIter1]; }
		}
	}
	return aPrimes;
}

ciaociao

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