第16章 数论问题 int compare(const bignum& A, const bignum& B) {

int I;

if (A.Len != B.Len) return A.Len > B.Len ? 1 : -1; for (I = A.Len - 1; I >= 0 && A[I] == B[I]; I--); if (I < 0) return 0;

return A[I] > B[I] ? 1 : -1; }

bignum operator+(const bignum& A, const bignum& B) {

bignum R; int I;

int Carry = 0;

for (I = 0; I < A.Len || I < B.Len || Carry > 0; I++) {

if (I < A.Len) Carry += A[I]; if (I < B.Len) Carry += B[I]; R[I] = Carry % Base; Carry /= Base; }

R.Len = I; return R; }

bignum operator-(const bignum& A, const bignum& B) {

bignum R; int Carry = 0; R.Len = A.Len; int I;

for (I = 0; I < R.Len; I++) {

R[I] = A[I] - Carry;

if (I < B.Len) R[I] -= B[I];

if (R[I] < 0) Carry = 1, R[I] += Base; else Carry = 0; }

while (R.Len > 0 && R[R.Len - 1] == 0) R.Len--; return R; }

247·

·

ACM程序设计培训教程

bignum operator*(const bignum& A, const int B) {

int I;

if (B == 0) return 0; bignum R;

hugeint Carry = 0;

for (I = 0; I < A.Len || Carry > 0; I++) {

if (I < A.Len) Carry += hugeint(A[I]) * B; R[I] = Carry % Base; Carry /= Base; }

R.Len = I; return R; }

bignum operator*(const bignum& A, const bignum& B) {

int I;

if (B.Len == 0) return 0; bignum R;

for (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[I]) * B[J]; if (I + J < R.Len) Carry += R[I + J];

if (I + J >= R.Len) R[R.Len++] = Carry % Base; else R[I + J] = Carry % Base; Carry /= Base; } }

return R; }

bignum operator/(const bignum& A, const int B) {

bignum R; int I;

hugeint C = 0;

for (I = A.Len - 1; I >= 0; I--)

248· ·

第16章 数论问题 {

C = C * Base + A[I]; R[I] = C / B; C %= B; }

R.Len = A.Len;

while (R.Len > 0 && R[R.Len - 1] == 0) R.Len--; return R; }

bignum operator/(const bignum& A, const bignum& B) {

int I;

bignum R, Carry = 0; int Left, Right, Mid;

for (I = A.Len - 1; I >= 0; I--) {

Carry = Carry * Base + A[I]; 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[I] = Left;

Carry = Carry - B * Left; }

R.Len = A.Len;

while (R.Len > 0 && R[R.Len - 1] == 0) R.Len--; return R; }

bool operator==(const bignum& A, const bignum& B) {

int i;

if(A.Len != B.Len)return 0; for(i=0;i

if(A.Data[i]!=B.Data[i])return 0; return 1; }

249·

·

ACM程序设计培训教程

bignum operator%(const bignum& A, const bignum& B) {

int I;

bignum R, Carry = 0; int Left, Right, Mid;

for (I = A.Len - 1; I >= 0; I--) {

Carry = Carry * Base + A[I]; 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[I] = Left;

Carry = Carry - B * Left; }

R.Len = A.Len;

while (R.Len > 0 && R[R.Len - 1] == 0) R.Len--; return Carry; }

istream& operator>>(istream& In, bignum& V) {

char Ch;

for (V = 0; In >> Ch;) {

V = V * 10 + (Ch - '0'); if (cin.peek() <= ' ') break; }

return In; }

ostream& operator<<(ostream& Out, const bignum& V) {

int I;

Out << (V.Len == 0 ? 0 : V[V.Len - 1]); for (I = V.Len - 2; I >= 0; I--)

for (int J = Base / 10; J > 0; J /= 10)

250· ·