//POJ_1001_recursive
#include <math.h>
#include <iostream>
#include <string>
using namespace std;
string AddString(string a, string b)
{
int len = a.length()>b.length() ? a.length() : b.length();
if(len == a.length()){
string auxi(len - b.length(), '0');
b = auxi + b;
}
else{
string auxi(len- a.length(), '0');
a = auxi + a;
}
int i;
string result = a;
int sum = 0;
int carry = 0;
for(i=len-1; i>=0; --i){
sum = a.at(i) + b.at(i) - '0' - '0' + carry;
carry = sum / 10;
result[i] = sum % 10 + '0';
}
if (carry != 0){
result = (char)(carry + '0') + result;
}
return result;
}
string multiply(const string &a, const string &b)
{
if(a.length() < 4 && b.length() < 4){//可以直接相乘，这里作为递归的终止条件
long aInt = atof(a.c_str());
long bInt = atof(b.c_str());
char buffer[100];
sprintf(buffer, "%d", aInt*bInt);
string result(buffer);
return result;
}
int aLen = a.length();
int bLen = b.length();
int aHalfLen = a.length() / 2;
int bHalfLen = b.length() / 2;
string str1_1 = a.substr(0, aHalfLen);
string str1_2 = a.substr(aHalfLen, aLen - aHalfLen);
string str2_1 = b.substr(0, bHalfLen);
string str2_2 = b.substr(bHalfLen, bLen-bHalfLen);
string str11 = multiply(str1_1, str2_1);
string str12 = multiply(str1_1, str2_2);
string str21 = multiply(str1_2, str2_1);
string str22 = multiply(str1_2, str2_2);
str12.append(aLen-aHalfLen, '0');
str21.append(bLen-bHalfLen, '0');
str11.append(aLen+bLen-aHalfLen-bHalfLen, '0');
string result = AddString(str11, str12);
result = AddString(result ,str21);
result = AddString(result ,str22);
return result;
}
int main()
{
freopen("E:\\test.txt", "rb", stdin);
int expo = 0;
char buff[100];
while(scanf("%s%d", buff, &expo) != EOF)
{
string str(buff);
int start = 0;
while(true){//越过开始的0
if(start <= str.length()-1 && str.at(start) == '0'){
++start;
}
else{
break;
}
}
int end = str.length()-1;
while(true){//越过结束的0
if(end >= 0 && str.at(end) == '0'){
--end;
}
else{
break;
}
}
if(start > end){
cout<<"0"<<endl;
continue;
}
str = str.substr(start, end - start + 1);
int pos = str.find('.');
int dot = str.length() - 1 - pos;
if(pos != -1){//删除小数点
str = str.erase(pos, 1);
}
int time = expo;
string str2 = str;
string str1 = str;
string result = "1";
if (time%2 != 0){
result = str;
}
time /= 2;
while(time){
str2 = multiply(str1, str1);
if (time%2 != 0){
result = multiply(result, str2);
}
time /= 2;
str1 = str2;
}
str2 = result;
if( pos == -1 )
{
}
else{
dot *= expo;
if(dot > str2.length()){
string auxi(dot - str2.length(), '0');
str2 = '.' + auxi + str2;
}
else{
str2.insert(str2.length() - dot, ".");
}
}
if(str2.at( str2.length()-1 ) == '.'){
str2.erase(str2.length()-1, 1);
}
cout<<str2<<endl;
}
return 0;
}
|
