やっつけ多倍長整数クラス

/**
 * Copyright uwi ( http://wonderfl.net/user/uwi )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/q0t5
 */

package {
    import flash.display.Sprite;
    import flash.text.TextField;
    import flash.utils.getTimer;
    
    // 0,正数のみ
    // 各桁をuintで持っているので無茶なことをすると簡単に破綻します。
    public class Test extends Sprite {
        private var _tf : TextField;
  
        public function Test() {
            _tf = new TextField();
            _tf.width = 465;
            _tf.height = 465;
            addChild(_tf);
            
            var s : int = getTimer();
            
            var a : MPI = new MPI("12345678901234567890");
            var b : MPI = new MPI("20092009");
            var c : int = 2009;
            tr("a", a);
            tr("b", b);
            tr("c", c);
            tr("a < b", MPI.comp(a, b));
            tr("a + b", MPI.add(a, b));
            tr("a + c", MPI.addint(a, c));
            tr("a - b", MPI.sub(a, b)); 
            tr("a - c", MPI.subint(a, c)); 
            tr("a * b", MPI.mul(a, b));
            tr("a * c", MPI.mulint(a, c));
            tr("a / b", MPI.div(a, b));
            tr("a / c", MPI.divint(a, c));
            var g : int = getTimer();
            tr((g - s) + " ms");
        }

        private function tr(...o : Array) : void
        {
            _tf.appendText(o + "\n");
        }
    }
}

class MPI
{
    public var d : Vector.<uint>;
    
    public function MPI(v : * = 0)
    {
        if(v is Number){
            d = Vector.<uint>([]);
            for(var n : Number = v;n != 0;n = Math.floor(n / 10))d.push(n % 10);
            if(v == 0)d.push(0);
        }else if(v is String){
            d = Vector.<uint>([]);
            for(var i : int = v.length - 1;i >= 0;i--){
                d.push(uint(v.charAt(i)));
            }
        }else if(v is Array){
            d = Vector.<uint>(v);
        }else if(v is Vector.<uint>){
            d = v.concat();
        }else if(v is MPI){
            d = v.d.concat();
        }
        if(d)shave();
    }
    
    public static function add(a : MPI, b : MPI) : MPI
    {
        var ret : MPI = new MPI(a);
        var i : int;
        var minl : int = Math.min(ret.d.length, b.d.length);
        for(i = 0;i < minl;i++){
            ret.d[i] += b.d[i];
        }
        for(i = ret.d.length;i < b.d.length;i++){
            ret.d.push(b.d[i]);
        }
        ret.carry();
        return ret;
    }
    
    public static function addint(a : MPI, b : int) : MPI
    {
        var ret : MPI = new MPI(a);
        ret.d[0] += b;
        ret.carry();
        return ret;
    }
    
    public static function sub(a: MPI, b : MPI) : MPI
    {
        if(comp(a, b) < 0){
            var m : MPI = a; a = b; b = m;
        }
        // a - b
        var ret : MPI = new MPI(a);
        var i : int;
        for(i = 0;i < b.d.length;i++){
            ret.d[i] -= b.d[i];
        }
        
        ret.minuscarry();
        return ret;
    }
    
    public static function subint(a : MPI, b : int) : MPI
    {
        var ret : MPI = new MPI(a);
        ret.d[0] -= b;
        ret.minuscarry();
        return ret;
    }
    
    public static function comp(a : MPI, b : MPI) : int
    {
        if(a.d.length != b.d.length)return a.d.length - b.d.length;
        for(var i : int = a.d.length - 1;i >= 0;i--){
            if(a.d[i] != b.d[i]){
                return a.d[i] - b.d[i];
            }
        }
        return 0;
    }
    
    public static function mul(a : MPI, b : MPI) : MPI
    {
        var retv : Vector.<uint> = new Vector.<uint>(a.d.length + b.d.length);
        var i : int, j : int;
        for(i = 0;i < retv.length;i++)retv[i] = 0;
        for(i = 0;i < a.d.length;i++){
            for(j = 0;j < b.d.length;j++){
                retv[i + j] += a.d[i] * b.d[j];
            }
        }
        var ret : MPI = new MPI(retv);
        ret.carry();
        ret.shave();
        return ret;
    }
    
    public static function mulint(a : MPI, b : int) : MPI
    {
        var ret : MPI = new MPI(a);
        for(var i : int = 0;i < ret.d.length;i++){
            ret.d[i] *= b;
        }
        ret.carry();
        return ret;
    }
    
    public static function div(a : MPI, b : MPI) : Array
    {
        var bm : Array = new Array(10);
        var i : int, j : int;
        for(i = 1;i <= 9;i++)bm[i] = mulint(b, i);
        
        var retr : Vector.<uint> = Vector.<uint>([]);
        var m : MPI = new MPI(0);
        for(i = a.d.length - 1;i >= 0;i--){
            m = addint(mulint(m, 10), a.d[i]);
            for(j = 1;j <= 9;j++){
                if(comp(m, bm[j]) < 0)break;
            }
            retr.push(j - 1);
            if(j >= 2)m = sub(m, bm[j - 1]);
        }
        
        var ret : MPI = new MPI(retr.reverse());
        ret.shave();
        m.shave();
        return [ret, m];
    }
    
    public static function divint(a : MPI, b : int) : Array
    {
        var i : int;
        
        var retr : Vector.<uint> = Vector.<uint>([]);
        var m : int = 0;
        for(i = a.d.length - 1;i >= 0;i--){
            m = m * 10 + a.d[i];
            var dv : int = m / b;
            retr.push(dv);
            m %= b;
        }
        
        var ret : MPI = new MPI(retr.reverse());
        ret.shave();
        return [ret, m];
    }
    
    // 位上げ
    public function carry() : void
    {
        for(var i : int = 0;i < d.length;i++){
            var c : uint = d[i] / 10;
            if(c > 0){
                if(i == d.length - 1){
                    d.push(0);
                }
                d[i + 1] += c;
            }
            d[i] %= 10;
        }
    }
    
    // 位下げ
    public function minuscarry() : void
    {
        for(var i : int = 0;i < d.length;i++){
            if(d[i] <= 2147483648)continue; // やっつけ
            var v : int = d[i] - 4294967296;
            var c : int = (-v + 9) / 10;
            d[i + 1] -= c;
            d[i] += 10 * c;
        }
        shave();
    }
    
    // 上位の桁から0を削る
    public function shave() : void
    {
        for(var i : int = d.length - 1;i >= 1;i--){
            if(d[i] > 0)break;
            d.pop();
        }
    }
    
    public function toString() : String
    {
        return d.concat().reverse().join('');
    } 
}