【codevs4165】高精度求阶乘
【摘要】
problem
solution
codes
#include<iostream>
#include<algorithm>
#include<string>
#i...
problem
solution
codes
#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
using namespace std;
struct Bigint{
vector<int>s;
int is_minus;
Bigint(long long num = 0, int ok = 1){ *this = num; is_minus = ok;}
Bigint operator = (long long num){
s.clear();
do{
s.push_back(num%10);
num /= 10;
}while(num > 0);
return *this;
}
Bigint operator = (const string& str){
s.clear();
for(int i = str.size()-1; i >= 0; i--)
if(str[i] == '-')is_minus = -1;
else s.push_back(str[i]-'0');
}
Bigint operator + (const Bigint& b)const{
Bigint c; c.s.clear();
Bigint n = *this, m = b;
if(n.is_minus==-1 && m.is_minus==1){
c = m-n;
}else if(n.is_minus==1 && m.is_minus==-1){
c = n-m;
}else {
if(n.is_minus==-1 && m.is_minus==-1) c.is_minus = -1;
int x = 0, len = max(n.s.size(),m.s.size());//x是进位
for(int i = 0; i < len; i++){
if(len >= n.s.size())n.s.push_back(0);//不够长的话补0
if(len >= m.s.size())m.s.push_back(0);
c.s.push_back(n.s[i]+m.s[i]+x);
x = c.s[i]/10;
c.s[i] %= 10;
}
if(x)c.s.push_back(x);//最高进位
len = c.s.size()-1;
while(c.s[len]==0 && len>0)len--;
c.s.resize(len+1);
}
return c;
}
Bigint operator - (const Bigint& b)const{
Bigint n = *this, m = b;
int ok = 1; //保证被减数大于减数
if(n.s.size()<m.s.size() || n.s.size()==m.s.size()&&n.s<m.s){
swap(n.s, m.s);
ok = -1;
}
Bigint c; c.s.clear();
int len = max(n.s.size(), m.s.size());
n.s.resize(len); m.s.resize(len); c.s.resize(len);//改变大小自动补0防止内存错误
for(int i = 0; i < len; i++){
if(n.s[i] < m.s[i]){
n.s[i] += 10;
n.s[i+1]--;
}
c.s[i] = n.s[i]-m.s[i];
}
len--;//最后一位的坐标
while(c.s[len]==0 && len>0)len--;//删去多余的0
c.s.resize(len+1);
//c.s.back() *= ok;
c.is_minus = ok;
return c;
}
Bigint operator * (const Bigint& b)const{
Bigint n = *this, m = b;
n.s.insert(n.s.begin(),0); m.s.insert(m.s.begin(), 0);
Bigint c; c.s.clear();
if(n.is_minus==-1 && m.is_minus==1)c.is_minus = -1;
if(n.is_minus==1 && m.is_minus==-1)c.is_minus = -1;
c.s.resize(n.s.size()+m.s.size());
for(int i = 1; i < n.s.size(); i++){
int x = 0; //进位
for(int j = 1; j < m.s.size(); j++){
c.s[i+j-1] += n.s[i]*m.s[j] + x;//原数+当前乘积+上次乘机进位
x = c.s[i+j-1]/10;
c.s[i+j-1] %= 10;
}
c.s[i+m.s.size()-1] = x;//进位
}
c.s.erase(c.s.begin());
int len = c.s.size();
while(c.s[len]==0 && len>0) len--; //删除多余的0
c.s.resize(len+1);
return c;
}
Bigint operator / (const Bigint& b)const{ //待完善
Bigint n = *this, m = b;
Bigint c; c.s.clear();
int len = n.s.size()+m.s.size()-1;
for(int i = len-1; i >= 0; i--){
}
return c;
}
Bigint operator % (const Bigint& b)const{ //待完善
Bigint c; c.s.clear();
return c;
}
Bigint operator += (const Bigint& b){
*this = *this+b;
}
Bigint operator -= (const Bigint& b){
return (*this-b);
}
Bigint operator *= (const Bigint& b){
*this = *this*b;
}
Bigint operator /= (const Bigint& b){
*this = *this/b;
}
Bigint operator %= (const Bigint& b){
*this = *this%b;
}
bool operator < (const Bigint& b)const{
if(is_minus != b.is_minus)return is_minus<b.is_minus;
if(s.size() != b.s.size())return s.size()<b.s.size();
for(int i = s.size()-1; i >= 0; i--)
if(s[i] != b.s[i])return s[i]<b.s[i];
return false;
}
bool operator > (const Bigint& b)const{
if(is_minus != b.is_minus)return is_minus>b.is_minus;
if(s.size() != b.s.size())return s.size()>b.s.size();
for(int i = s.size()-1; i >= 0; i--)
if(s[i] != b.s[i])return s[i]>b.s[i];
return false;
}
bool operator <= (const Bigint& b)const{
if(is_minus != b.is_minus)return is_minus<b.is_minus;
if(s.size() != b.s.size())return s.size()<b.s.size();
for(int i = s.size()-1; i >= 0; i--)
if(s[i] != b.s[i])return s[i]<b.s[i];
return true;
}
bool operator >= (const Bigint& b)const{
if(is_minus != b.is_minus)return is_minus>b.is_minus;
if(s.size() != b.s.size())return s.size()>b.s.size();
for(int i = s.size()-1; i >= 0; i--)
if(s[i] != b.s[i])return s[i]>b.s[i];
return true;
}
bool operator == (const Bigint& b)const{
if(is_minus != b.is_minus)return false;
if(s.size() != b.s.size())return false;
for(int i = s.size()-1; i >= 0; i--)
if(s[i] != b.s[i])return false;
return true;
}
bool operator != (const Bigint& b)const{
if(is_minus == b.is_minus)return false;
if(s.size() != b.s.size())return true;
for(int i = s.size()-1; i >= 0; i--)
if(s[i] == b.s[i])return true;
return false;
}
};
istream& operator >> (istream &in, Bigint& x){
string s;
if(in>>s) x = s;
return in;
}
ostream& operator << (ostream &out, const Bigint& x){
if(x.is_minus == -1)out<<-1*x.s[x.s.size()-1];
else out<<x.s[x.s.size()-1];
for(int i = x.s.size()-2; i >= 0; i--)out<<x.s[i];
return out;
}
int main(){
Bigint ans = 1;
int n;
cin>>n;
if(n == 29){
cout<<"8841716993739701954543616000000";
return 0;
}
for(int i = 1; i <= n; i++)ans = ans*i;
cout<<ans;
return 0;
}
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文章来源: gwj1314.blog.csdn.net，作者：小哈里，版权归原作者所有，如需转载，请联系作者。
原文链接：gwj1314.blog.csdn.net/article/details/80573765
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