Project Euler 251(unsolved)
@see http://projecteuler.net/index.php?section=problems&id=251
♥0 |
Line 210 |
Modified 2010-05-17 10:57:25 |
MIT License
archived:2017-03-20 06:44:15
ActionScript3 source code
/**
* Copyright uwi ( http://wonderfl.net/user/uwi )
* MIT License ( http://www.opensource.org/licenses/mit-license.php )
* Downloaded from: http://wonderfl.net/c/sC59
*/
package {
import flash.display.Sprite;
import flash.text.TextField;
import flash.utils.getTimer;
import flash.events.*;
import com.bit101.components.*;
// @see http://projecteuler.net/index.php?section=problems&id=251
public class Euler251 extends Sprite {
private var _tf : TextField;
private var _primes : Array;
public function Euler251() {
_tf = new TextField();
_tf.width = 465;
_tf.height = 465;
addChild(_tf);
var pb : PushButton = new PushButton(this, 350, 10);
pb.label = "stop";
pb.width = 100;
pb.addEventListener(MouseEvent.CLICK, function(e : MouseEvent) : void
{
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
});
_s = getTimer();
solve();
tr((getTimer() - _s) + " ms");
}
private var _s : int;
// private static const N : int = 110000000;
private static const N : int = 1000;
private var ct : Number;
private var m : uint;
private var M : int;
// b^2 c = a^2 - ((1-2a)/3)^3
// -> a = 2(mod 3)
// a = 3m - 1として
// 右辺=(8m-3)m^2
private function solve() : void
{
var start : int = 0;
var end : int = N;
do{
var mid : int = (start + end) >> 1;
if(mid * mid * (8 * mid - 3) - 4 / 27 * Math.pow(N - (3 * mid - 1), 3) > 0){
end = mid;
}else{
start = mid;
}
}while(end - start > 1);
M = start + 1;
tr("M : " + M);
// M += 100;
_primes = doEratosthenes(Math.sqrt(8 * M - 3));
_primes.shift();
_ccs = new Array(M);
var i : uint;
for(i = 0;i < M;i++){
_ccs[i] = 8 * i + 5;
}
for each(var p : uint in _primes){
var pp : uint = p * p;
var inv8 : uint = exmod(8, totient(pp) - 1, pp);
var cor : uint = (inv8 * (pp - 5)) % pp;
for(i = cor;i < M;i += pp){
while(_ccs[i] % pp == 0){
_ccs[i] /= pp;
}
}
// tr(p, inv8, cor);
}
addEventListener(Event.ENTER_FRAME, onEnterFrame);
/*
for(i = M-100;i < M;i++){
tr(i, _ccs[i]);
}
var xxx : Number = 16224756;
tr(Math.sqrt((8 * xxx - 3) / _ccs[xxx-1]));
*/
m = 16000001;
// m = 1;
ct = 0;
}
private var _ccs : Array;
private function exmod(a : uint, b : uint, m : uint) : uint
{
var i : uint;
var ret : Number = 1;
var mul : Number = a;
for(i = b;i;i >>>= 1){
if(i & 1){
ret = (ret * mul) % m;
}
mul = (mul * mul) % m;
}
return ret;
}
private function onEnterFrame(e : Event) : void
{
var goal : int = m + 200000;
var i : int, j : uint, k : uint, p : int;
for(;m < goal && m <= M;m++){
/*
var cc : int = 8 * m - 3;
var sc : Number = Math.sqrt(cc);
var bb : int = m;
for each(p in _primes){
if(p > sc)break;
while(cc % (p * p) == 0){
cc /= (p * p);
sc /= p;
bb *= p;
}
}
*/
var cc : Number = _ccs[m-1];
var X : Number = m * m * (8 * m - 3);
var bb : Number = Math.sqrt((8 * m - 3) / _ccs[m-1]) * m;
var f : Object = factor(bb);
var divs : Array = [1];
for(var keystr : String in f){
var key : uint = uint(keystr);
var val : uint = f[keystr];
var lim : uint = divs.length;
for(i = 0, j = key;i < val;i++, j *= key){
for(k = 0;k < lim;k++){
divs.push(divs[k] * j);
}
}
}
if(m > 16224700){
tr(m, bb, divs);
}
var a : uint = 3 * m - 1;
var c : Number;
for each(var b : Number in divs){
c = cc * (bb / b) * (bb / b);
if(a + b + c <= N){
// if(m > 16200000){
// tr(a,b,c,m);
// }
ct++;
}
}
}
if(m > M){
tr("solved! " + (getTimer() - _s) + "ms");
tr(ct);
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
}
if(m % 200000 == 1)tr(m, ct, (getTimer() - _s) + "ms");
}
private var _ps : Array = doEratosthenes(Math.sqrt(16224756));
private function factor(n : int) : Object
{
var ret : Object = {};
for each(var i : uint in _ps){
if(i * i > n)break;
var ct : int = 0;
while(n % i == 0){
n /= i;
ct++;
}
if(ct > 0){
ret[i] = ct;
}
}
if(n != 1){
ret[n] = 1;
}
return ret;
}
private function doEratosthenes(n : int) : Array
{
var nn : uint = ((n / 2 - 1) >>> 5) + 1;
var ar : Vector.<uint> = new Vector.<uint>(nn);
var i : uint, j : uint;
for(i = 0;i < nn - 1;i++)ar[i] = 0xffffffff;
ar[nn - 1] = (1 << ((n / 2 - 1) & 31)) - 1;
var sq : uint = (Math.sqrt(n) - 3) >>> 1;
for(var p : uint = 0;p <= sq;p++){
if(ar[p >>> 5] & (1 << (p & 31))){
var m : uint = (p << 1) + 3;
var m2 : uint = m << 1;
for(var mm : uint = m * m;mm <= n;mm += m2){
var ind : uint = (mm - 3) >>> 1;
ar[ind >>> 5] &= ~(1 << (ind & 31));
}
}
}
var ret : Array = [2];
for(i = 0;i < nn;i++){
for(j = 0;j <= 31;j++){
if(ar[i] & (1 << j))ret.push((((i << 5) | j) << 1) + 3);
}
}
return ret;
}
private function totient(n : uint) : uint
{
if(n == 0)return 0;
var ret : uint = n;
for(var x : uint = 2;x * x <= n;++x){
if(n % x == 0){
ret -= ret / x;
do{n /= x;}while(n % x == 0);
}
}
if(n > 1)ret -= ret / n;
return ret;
}
private function carmichaelLambda(n : uint) : uint
{
var ret : uint = 1;
if(n % 8 == 0)n /= 2;
for(var d : uint = 2;d <= n;d++){
if(n % d == 0){
var y : uint = d - 1;
n /= d;
while(n % d == 0){
n /= d;
y *= d;
}
ret = ret * y / GCD(ret, y);
}
}
return ret;
}
private function GCD(a : uint, b : uint) : uint
{
while(b > 0){
var c : uint = a;
a = b;
b = c % b;
}
return a;
}
private function tr(...o : Array) : void
{
_tf.appendText(o + "\n");
_tf.scrollV = _tf.maxScrollV;
}
}
}