delete pics to save space

history_source/信息学奥赛一本通/2.1.5.cpp

@@ -0,0 +1,124 @@
+//#include<algorithm>
+//#include<ctime>
+using namespace std;
+#include<iostream>
+#include<string>
+#include<vector>
+#include<cmath>
+struct bigNum
+{
+	static const int BASE=100000000,SIZE=8;
+	vector<int>num;
+	void clear()
+	{
+		while(num[0]==0&&num.size()>1) num.erase(num.begin());
+		if(num.size()==0) num.push_back(0);
+	}
+	bigNum operator=(string b)
+	{
+		num.clear();
+		for(int i=0;i<b.size();i++)
+		{
+			if(i%SIZE==0) num.insert(num.begin(),0);
+			num[0]+=(b[b.size()-1-i]-'0')*pow(10,i%SIZE);
+		}
+		while(num[0]==0&&num.size()>1) num.erase(num.begin());
+	}
+	bool operator==(bigNum b)
+	{
+		bigNum a;
+		a.num=num;
+		a.clear();
+		b.clear();
+		if(a.num==b.num) return 1;
+		return 0;
+	}
+	bigNum operator+(bigNum b)
+	{
+		bigNum a;
+		a.num=num;
+		a.clear();
+		b.clear();
+		if(a.num.size()<b.num.size())
+		{
+			bigNum c=a;
+			a=b;
+			b=c;
+		}
+		int ai,bi;
+		int j=0;
+		for(ai=a.num.size()-1,bi=b.num.size()-1;bi>=0;ai--,bi--)
+		{
+			a.num[ai]=a.num[ai]+b.num[bi]+j;
+			j=a.num[ai]/BASE;
+			a.num[ai]=a.num[ai]%BASE;
+		}
+		while(ai>=0&&j)
+		{
+			a.num[ai]+=j;
+			j=a.num[ai]/BASE;
+			a.num[ai]=a.num[ai]%BASE;
+			ai--;
+		}
+		if(j) a.num.insert(a.num.begin(),1);
+		a.clear();
+		return a;
+	}
+	bigNum operator*(int b)
+	{
+		bigNum a;
+		a.num=num;
+		a.clear();
+		long long add,j=0;
+		for(int i=a.num.size()-1;i>=0;i--)
+		{
+			add=(long long)a.num[i]*b+j;
+			j=add/BASE;
+			add=add%BASE;
+			a.num[i]=add;
+		}
+		if(j) a.num.insert(a.num.begin(),j);
+		a.clear();
+		return a;
+	}
+};
+ostream& operator<<(ostream &a,bigNum b)
+{
+	b.clear();
+	a<<b.num[0];
+	int x;
+	for(int i=1;i<b.num.size();i++)
+	{
+		x=b.num[i];
+		if(x<10) a<<"0000000";
+		else if(x<100) a<<"000000";
+		else if(x<1000) a<<"00000";
+		else if(x<10000) a<<"0000";
+		else if(x<100000) a<<"000";
+		else if(x<1000000) a<<"00";
+		else if(x<10000000) a<<"0";
+		a<<x; 
+	}
+	return a;
+}
+istream& operator>>(istream &a,bigNum &b)
+{
+	char x;
+	string zhuan;
+	while(a.get(x),x>='0'&&x<='9') zhuan+=x;
+	b=zhuan;
+	return a;
+}
+int main()
+{
+	ios::sync_with_stdio(false); 
+	bigNum ans;
+	ans="1";
+	int n;
+	cin>>n;
+//	int runTime=clock();
+	for(int i=1;i<=n;i++) ans=ans*i;
+	cout<<ans<<endl;
+//	cout<<"time used "<<clock()-runTime<<" ms"<<endl;
+	return 0;
+}