HDU1134，HDU1261 大数

用以前的C改了个大数类,又机制地水了几题...

#ifndef HEADER_BIGINT#define HEADER_BIGINT#include <iostream>#include <iomanip>#include <string>using namespace std;class BigInt{public:BigInt();BigInt(int smallNum);BigInt(const BigInt &bigNum);BigInt(string num);//todo...~BigInt();BigInt& operator =(const BigInt &rhs);BigInt operator +(const BigInt &rhs)const;BigInt operator -(const BigInt &rhs)const;BigInt operator *(const BigInt &rhs)const;BigInt operator /(const BigInt &rhs)const;//大数除大数,单纯靠减法，速度太慢...BigInt operator /(const int rhs)const;//大数除整型,速度还可以，但如果除超过WEI * WEI的数会有问题//因为其实现需要整数除法，WEI^3大于32位范围friend ostream& operator <<(ostream &out,const BigInt &bigNum);friend istream& operator >>(istream &in,BigInt &bigNum);//todo...private:void add(const int *a,const int *b,int *res)const;//a中数据与b中相加放入res中void sub(const int *a,const int *b,int *res)const;//void mul(const int *a,const int *b,int *res)const;//void div(const int *a,const int *b,int *res)const;//    bool larger(const int *a,const int *b)const;//a表示数据大于b表示数据则返回真    int realLen(const int *arr)const;//返回数组arr所表示数据真正占据数组长度void shiftLeft(int *arr,int cnt)const;//数组左移cnt位，空出位填0，用于除法void shiftRight(int *arr,int cnt)const;//数组右移cnt位，空出位填0，用于除法void alloc();//为构造函数申请digits的空间static const int LEN;static const int WEI;enum SIGN{POSI,NEGI} sign;//数据符号位int *digits;//真正的数据};//最长表示数据LEN * WEI位const int BigInt::LEN = 105;//缓冲区长度const int BigInt::WEI = 10000;//每一位权重ostream& operator <<(ostream &out,const BigInt &bigNum){if(bigNum.sign == BigInt::NEGI){out << "-";}//计算WEI的长度用于下面的格式化输出,第一次直接用4，结果改了WEI就悲剧了int bitWidth = -1;int wei = BigInt::WEI;while(wei > 0){bitWidth++;wei /= 10;}int len = bigNum.realLen(bigNum.digits);out << bigNum.digits[len - 1];for(int i = len - 2;i >= 0;i--){out.width(bitWidth);out.fill('0');out << bigNum.digits[i];}return out;}#endif

其实写的一团糟+_+

#include "BigInt.h"#include <string.h>BigInt::BigInt(){sign = POSI;alloc();}BigInt::BigInt(int smallNum){alloc();if(smallNum < 0){this ->sign = NEGI;smallNum = -smallNum;}int num = smallNum;int p = 0;while(num > 0){digits[p++] = num % WEI;num /= WEI;}}BigInt::BigInt(const BigInt &bigNum){alloc();this ->sign = bigNum.sign;for(int i = 0;i < LEN;i++){this ->digits[i] = bigNum.digits[i];}}BigInt::~BigInt(){delete digits;}void BigInt::alloc(){sign = POSI;digits = new int[LEN];for(int i = 0;i < LEN;i++){digits[i] = 0;}}BigInt& BigInt::operator =(const BigInt &rhs){if(this ->digits == NULL){alloc();}this ->sign = rhs.sign;for(int i = 0;i < LEN;i++){this ->digits[i] = rhs.digits[i];}return *this;}BigInt BigInt::operator +(const BigInt &rhs)const{BigInt res;if(this ->sign == POSI && rhs.sign == NEGI){BigInt t(rhs);t.sign = POSI;return *this - t;}else if(this ->sign == NEGI && rhs.sign == POSI){BigInt t(*this);t.sign = POSI;return rhs - t;}else if(this ->sign == NEGI && rhs.sign == NEGI){res.sign = NEGI;add(this ->digits,rhs.digits,res.digits);}else{res.sign = POSI;add(this ->digits,rhs.digits,res.digits);}return res;}void BigInt::add(const int *a,const int *b,int *res)const{int carry = 0;int len = realLen(a) > realLen(b) ? realLen(a) : realLen(b);for(int i = 0;i <= len;i++){res[i] = (a[i] + b[i] + carry) % WEI;carry = (a[i] + b[i] + carry) / WEI;}}BigInt BigInt::operator -(const BigInt &rhs)const{BigInt res;if(this ->sign == POSI && rhs.sign == NEGI){res.sign = POSI;add(this ->digits,rhs.digits,res.digits);}else if(this ->sign == NEGI && rhs.sign == NEGI){BigInt t(rhs);t.sign = POSI;return *this + t;}else if(this ->sign == NEGI && rhs.sign == POSI){res.sign = NEGI;add(this ->digits,rhs.digits,res.digits);}else{if(larger(this ->digits,rhs.digits)){res.sign = POSI;sub(this ->digits,rhs.digits,res.digits);}else{res.sign = NEGI;sub(rhs.digits,this ->digits,res.digits);}}return res;}void BigInt::sub(const int *a,const int *b,int *res)const{int carry = 0;for(int i = 0;i < realLen(a);i++){int t = a[i] - b[i] - carry;res[i] = (t + WEI) % WEI;carry = 1 - (t + WEI) / WEI;}}BigInt BigInt::operator *(const BigInt &rhs)const{BigInt res;if(this ->sign  ^ rhs.sign){res.sign = NEGI;}else{res.sign = POSI;}mul(this ->digits,rhs.digits,res.digits);return res;}void BigInt::mul(const int *a,const int *b,int *res)const{for(int i = 0;i <= realLen(a);i++){int carry = 0;for(int j = 0;j <= realLen(b) && i + j < LEN;j++){int s = res[i + j] + a[i] * b[j] + carry;res[i + j] = s % WEI;carry = s / WEI;}}}BigInt BigInt::operator /(const int rhs)const{BigInt res;if(this ->sign ^ (rhs < 0)){res.sign = NEGI;}else{res.sign = POSI;}int carry = 0;for(int i = realLen(this ->digits) - 1;i >= 0;i--){res.digits[i] = (this ->digits[i] + carry * WEI) / rhs;carry = (this ->digits[i] + carry * WEI) % rhs;}return res;}BigInt BigInt::operator /(const BigInt &rhs)const{BigInt res;if(this ->sign ^ rhs.sign){res.sign = NEGI;}else{res.sign = POSI;}int *ta = new int[LEN];memcpy(ta,this ->digits,sizeof(int) * LEN);int *tb = new int[LEN];memcpy(tb,rhs.digits,sizeof(int) * LEN);div(ta,tb,res.digits);delete tb;delete ta;return res;}void BigInt::div(const int *a,const int *b,int *res)const{int la = realLen(a);int lb = realLen(b);if(la < lb){return;}int *ta = new int[LEN];memcpy(ta,a,sizeof(int) * LEN);int *tb = new int[LEN];memcpy(tb,b,sizeof(int) * LEN);shiftLeft(tb,la -lb);for(int i = la - lb;i >= 0;i--){while(!larger(tb,ta)){res[i]++;sub(ta,tb,ta);}shiftRight(tb,1);}delete ta;delete tb;}void BigInt::shiftLeft(int *arr,int cnt)const{for(int i = LEN - 1;i >= cnt;i--){arr[i] = arr[i - cnt];}for(int i = cnt - 1;i >= 0;i--){arr[i] = 0;}}void BigInt::shiftRight(int *arr,int cnt)const{for(int i = LEN - 1;i > LEN - 1 - cnt;i--){arr[i] = 0;}for(int i = 0;i < LEN - cnt;i++){arr[i] = arr[i + cnt];}}bool BigInt::larger(const int *a,const int *b)const{for(int i = LEN - 1;i >= 0;i--){if(a[i] > b[i]){return true;}else if(a[i] < b[i]){return false;}}return false;}int BigInt::realLen(const int *arr)const{int len = LEN - 1;while(arr[len] == 0 && len > 0){len--;}return len + 1;}