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[323344] 主题： 大数类例程
作者： little (渺小・Happy^_^)
标题： 大数类例程[转载]
来自： 192.168.*.*
发贴时间： 2005年01月19日 14:18:10 (UTC +08:00)
长度： 3143字

#include <iostream>
#include <memory>

using namespace std;

#define for if (0); else for

typedef __int64 hugeint;

struct xnum
{
enum {Base = 1000000000};
enum {Capacity = 20};
int Len;
int Data;
xnum() : Len(0) {}
xnum(const xnum& V) : Len(V.Len) { memcpy(Data, V.Data, Len * sizeof *Data); }
xnum(int V) : Len(0) { for (; V > 0; V /= Base) Data = V % Base; }
xnum& operator=(const xnum& V) { Len = V.Len; memcpy(Data, V.Data, Len * sizeof
*Data); return *this; }
int& operator(int Index) { return Data; }
int operator(int Index) const { return Data; }
};

int compare(const xnum& A, const xnum& B)
{
if (A.Len != B.Len) return A.Len > B.Len ? 1 : -1;
int I;
for (I = A.Len - 1; I >= 0 && A == B; I--);
if (I < 0) return 0;
return A > B ? 1 : -1;
}

xnum operator+(const xnum& A, const xnum& B)
{
xnum R;
int I, Carry = 0;
for (I = 0; I < A.Len || I < B.Len || Carry > 0; I++)
{
if (I < A.Len) Carry += A;
if (I < B.Len) Carry += B;
R = Carry % Base;
Carry /= Base;
}
R.Len = I;
return R;
}

xnum operator-(const xnum& A, const xnum& B)
{
xnum R;
int Carry = 0;
R.Len = A.Len;
for (int I = 0; I < R.Len; I++)
{
R = A - Carry;
if (I < B.Len) R -= B;
if (R < 0) Carry = 1, R += Base;
else Carry = 0;
}
while (R.Len > 0 && R == 0) R.Len--;
return R;
}

xnum operator*(const xnum& A, const int B)
{
if (B == 0) return 0;
xnum R;
hugeint Carry = 0;
int I;
for (I = 0; I < A.Len || Carry > 0; I++)
{
if (I < A.Len) Carry += hugeint(A) * B;
R = Carry % Base;
Carry /= Base;
}
R.Len = I;
return R;
}

xnum operator*(const xnum& A, const xnum& B)
{
if (B.Len == 0) return 0;
xnum R;
for (int I = 0; I < A.Len; I++)
{
hugeint Carry = 0;
for (int J = 0; J < B.Len || Carry > 0; J++)
{
if (J < B.Len) Carry += hugeint(A) * B;
if (I + J < R.Len) Carry += R;
if (I + J >= R.Len) R = Carry % Base;
else R = Carry % Base;
Carry /= Base;
}
}
return R;
}

xnum operator/(const xnum& A, const int B)
{
xnum R;
hugeint C = 0;
for (int I = A.Len - 1; I >= 0; I--)
{
C = C * Base + A;
R = C / B;
C %= B;
}
R.Len = A.Len;
while (R.Len > 0 && R == 0) R.Len--;
return R;
}

xnum operator/(const xnum& A, const xnum& B)
{
xnum R, Carry = 0;
int Left, Right, Mid;
for (int I = A.Len - 1; I >= 0; I--)
{
Carry = Carry * Base + A;
Left = 0;
Right = Base - 1;
while (Left < Right)
{
Mid = (Left + Right + 1) / 2;
if (compare(B * Mid, Carry) <= 0) Left = Mid;
else Right = Mid - 1;
}
R = Left;
Carry = Carry - B * Left;
}
R.Len = A.Len;
while (R.Len > 0 && R == 0) R.Len--;
return R;
}

istream& operator>>(istream& In, xnum& V)
{
char Ch;
for (V = 0; In >> Ch;)
{
V = V * 10 + (Ch - '0');
if (cin.peek() <= ' ') break;
}
return In;
}

ostream& operator<<(ostream& Out, const xnum& V)
{
Out << (V.Len == 0 ? 0 : V);
for (int I = V.Len - 2; I >= 0; I--) for (int J = xnum::Base / 10; J > 0; J /= 10) Out <<
; V / J % 10;
return Out;
}

int main()
{
return 0;
}


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