大数算法

#include <iostream> #include <string> #include <map> #include <vector> #include <cstring> #include <iomanip> #define MAXN 9999 #define DLEN 4 using namespace std; class BigNum{ private: int a[300]; int len; public: BigNum() { len = 1; memset(a,0,sizeof(a)); } BigNum(const int b); BigNum(const char* b); BigNum(const BigNum & T); bool Bigger(const BigNum &) const; BigNum & operator=(const BigNum &); BigNum & Add(const BigNum &); BigNum & Sub(const BigNum &); BigNum operator+(const BigNum &) const; BigNum operator-(const BigNum &) const; BigNum operator*(const BigNum &) const; BigNum operator/(const int &) const; void Print(); BigNum operator+=(const BigNum &) ; BigNum operator-=(const BigNum &) ; BigNum operator*=(const BigNum &) ; BigNum operator/=(const int &) ; }; BigNum::BigNum(const int b) { int c,d = b; len = 0; memset(a,0,sizeof(a)); while(d > MAXN) { c = d - d / (MAXN + 1) * (MAXN + 1); d = d / (MAXN + 1); a[len++] = c; } a[len++] = d; } BigNum::BigNum(const BigNum & T) : len(T.len) { int i; memset(a,0,sizeof(a)); for(i = 0 ; i < len ; i++) a[i] = T.a[i]; } bool BigNum::Bigger(const BigNum & T) const { int ln; if(len > T.len) return true; else if(len == T.len) { ln = len - 1; while(a[ln] == T.a[ln] && ln >= 0) ln--; if(ln >= 0 && a[ln] > T.a[ln]) return true; else return false; } else return false; } BigNum & BigNum::operator=(const BigNum & n) { len = n.len; memset(a,0,sizeof(a)); for(int i = 0 ; i < len ; i++) a[i]=n.a[i]; return *this; } BigNum & BigNum::Add(const BigNum & T) { int i,big; big = T.len > len ? T.len : len; for(i = 0 ; i < big ; i++) { a[i] = a[i] + T.a[i]; if(a[i] > MAXN) { a[i + 1]++; a[i] = a[i] - MAXN - 1; } } if(a[big] != 0) len = big + 1; else len = big; return *this; } BigNum & BigNum::Sub(const BigNum & T) { int i,j,big; big = T.len > len ? T.len : len; for(i = 0 ; i < big ; i++) { if(a[i] < T.a[i]) { j = i + 1; while(a[j] == 0) j++; a[j--]--; while(j > i) a[j--] += MAXN; a[i] = a[i] + MAXN + 1 - T.a[i]; } else a[i] -= T.a[i]; } len = big; while(a[len - 1] == 0 && len > 1) len--; return *this; } BigNum BigNum::operator+(const BigNum & n) const { BigNum a = *this; a.Add(n); return a; } BigNum BigNum::operator-(const BigNum & T) const { BigNum b = *this; b.Sub(T); return b; } BigNum BigNum::operator*(const BigNum & T) const { BigNum ret; int i,j,up; int temp,temp1; for(i = 0 ; i < len ; i++) { up = 0; for(j = 0 ; j < T.len ; j++) { temp = a[i] * T.a[j] + ret.a[i + j] + up; if(temp > MAXN) { temp1 = temp - temp / (MAXN + 1) * (MAXN + 1); up = temp / (MAXN + 1); ret.a[i + j] = temp1; } else { up = 0; ret.a[i + j] = temp; } } if(up != 0) ret.a[i + j] = up; } ret.len = i + j; while(ret.a[ret.len - 1] == 0 && ret.len > 1) ret.len--; return ret;} BigNum BigNum::operator/(const int & b) const { BigNum ret; int i,down = 0; for(i = len - 1 ; i >= 0 ; i--) { ret.a[i] = (a[i] + down * (MAXN + 1)) / b; down = a[i] + down * (MAXN + 1) - ret.a[i] * b; } ret.len = len; while(ret.a[ret.len - 1] == 0) ret.len--; return ret; } void BigNum::Print(){ int i; cout << a[len - 1]; for(i = len - 2 ; i >= 0 ; i--) { cout.width(DLEN); cout.fill('0'); cout << a[i]; } cout << endl; } BigNum::BigNum(const char* b) { int temp=0,numlen=1; int ca=0; len = 0; memset(a,0,sizeof(a)); while(b[ca++] != '/0'); ca--; while(--ca >= 0) { temp += numlen * (b[ca]-'0'); numlen*=10; if( numlen==(MAXN + 1) ) { a[len++]=temp; numlen=1; temp=0; } } if(temp!=0) { a[len++]=temp; } } BigNum BigNum::operator*=(const BigNum & T) { BigNum ret; int i,j,up; int temp,temp1; for(i = 0 ; i < len ; i++) { up = 0; for(j = 0 ; j < T.len ; j++) { temp = a[i] * T.a[j] + ret.a[i + j] + up; if(temp > MAXN) { temp1 = temp - temp / (MAXN + 1) * (MAXN + 1); up = temp / (MAXN + 1); ret.a[i + j] = temp1; } else { up = 0; ret.a[i + j] = temp; } } if(up != 0) ret.a[i + j] = up; } ret.len = i + j; while(ret.a[ret.len - 1] == 0 && ret.len > 1) ret.len--; *this=ret; return *this; } BigNum BigNum::operator/=(const int & b) { BigNum ret; int i,down = 0; for(i = len - 1 ; i >= 0 ; i--) { ret.a[i] = (a[i] + down * (MAXN + 1)) / b; down = a[i] + down * (MAXN + 1) - ret.a[i] * b; } ret.len = len; while(ret.a[ret.len - 1] == 0) ret.len--; *this=ret; return *this; } BigNum BigNum::operator+=(const BigNum & n) { this->Add(n); return *this; } BigNum BigNum::operator-=(const BigNum & T) { this->Sub(T); return *this; }