//大數相除 
//調用形式：N.Div(A)，返回值：N/A 
//除法的關鍵在于“試商”，然后就變成了乘法和減法 
//這里將被除數與除數的試商轉化成了被除數最高位與除數最高位的試商 
CBigInt CBigInt::Div(CBigInt& A) 
{ 
CBigInt X,Y,Z; 
int len; 
unsigned __int64 num,div; 
unsigned long carry=0; 
Y.Mov(*this); 
while(Y.Cmp(A)>0) 
{ 
if(Y.m_ulvalue[Y.m_nLength-1]>A.m_ulvalue[A.m_nLength-1]) 
{ 
len=Y.m_nLength-A.m_nLength; 
div=Y.m_ulvalue[Y.m_nLength-1]/(A.m_ulvalue[A.m_nLength-1]+1); 
} 
else if(Y.m_nLength>A.m_nLength) 
{ 
len=Y.m_nLength-A.m_nLength-1; 
num=Y.m_ulvalue[Y.m_nLength-1]; 
num=(num<<32)+Y.m_ulvalue[Y.m_nLength-2]; 
if(A.m_ulvalue[A.m_nLength-1]==0xffffffff)div=(num>>32); 
else div=num/(A.m_ulvalue[A.m_nLength-1]+1); 
} 
else 
{ 
X.Mov(X.Add(1)); 
break; 
} 
Z.Mov(div); 
Z.m_nLength+=len; 
for(int i=Z.m_nLength-1;i>=len;i--)Z.m_ulvalue[i]=Z.m_ulvalue[i-len]; 
for(i=0;i<len;i++)Z.m_ulvalue[i]=0; 
X.Mov(X.Add(Z)); 
Z.Mov(Z.Mul(A)); 
Y.Mov(Y.Sub(Z)); 
} 
if(Y.Cmp(A)==0)X.Mov(X.Add(1)); 
if(m_nSign+A.m_nSign==1)X.m_nSign=0; 
else X.m_nSign=1; 
return X; 
}