748UVa 高精度幂R^n (0<R<99.999, 0<n<=25)

#include<stdio.h>
#include<string.h>
class db
{
public:
	int d[500];
	int len;
	int pos;
	void clean( );
	db operator=(char* s);
	db();
	db(char* s);
	void display();
	db operator* (const db d) const;
};
void db::clean()
{
	int p = pos;
	int l = len;
	int dd[300];
	for(int k = 0; k < 300; k++)
	{
		dd[k] = d[k];
	}


	int i;
	for(i = 0; i < p; i++)
		if(dd[i] != 0) break;
	len = 0;
	for(int j = i; i!=p && j < p; j++)         //i!=p
	{
		d[len++] = dd[j];
	}


	pos = len;
	for(i = l-1; i>= p; i--)                //p!=len
	{
		if(dd[i] != 0) break;
	}
	for(int j = p; p!= l && j<=i; j++)
	{
		d[len++] = dd[j];;
	}


}
db::db()
{
	len = 1 ;              //结果为db的0？R!=0
	pos = 0;
	memset(d,0, sizeof(d));
}
db::db(char* s)
{
	*this = s;
}
db db::operator=(char* s)
{
	memset(d, 0, sizeof(d));
	len = 0;
	pos = -1;
	for(int i = 0; i < strlen(s); i++)
	{
		if(s[i] == '.')
			pos = i;
		else d[len++] = s[i]-'0';
	}
	if(pos == -1) pos = len;
	


	this->clean();


	//reverse
	int temp;
	for(int re = 0; re < len/2; re++)
	{
		temp = d[re];
		d[re] = d[len-1-re];
		d[len-1-re] = temp;
	}
	pos = len-pos;


	return *this;
}
void db::display()
{
	int i;


	for(i = len-1; i >= pos; i--)
		printf("%d", d[i]);
	
	if(pos != 0)
	{
	putchar('.');
	for(; i >= 0; i--)
		printf("%d", d[i]);
	putchar('\n');
	}
}
db db::operator*(const db rhs) const
{
	db res;
	int prd;
	for(int i = 0; i < len; i++)
	{
		for(int j = 0; j < rhs.len; j++)
		{
			prd =res.d[i+j]+d[i]*rhs.d[j];
			res.d[i+j] = prd%10;
			res.d[i+j+1] += prd/10;
		}
	}
	res.pos = pos+rhs.pos;
	res.len = len+rhs.len;
	res.clean();
	/*
	printf("hi:");
	res.display();
	*/


	return res;
}
int main()
{
	//
	freopen("input.txt", "r", stdin);
	char r[30000];
	int n;


	while(scanf("%s %d", r, &n) == 2)
	{
		db res =r;
		for(int i = 1; i < n; i++)
		{
			res = res*r;
		}
		res.display();
	}
	
}