Problem 16 Power digit sum （高精度幂）

Power digit sum

Problem 16

215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.

What is the sum of the digits of the number 21000?

Answer: 1366 Completed on Wed, 26 Oct 2016, 15:22

题解：高精度幂。

代码：

#include<iostream>
#include<cstdio>
#include<cctype>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<string>
#include<vector>
#include<queue>
#include<map>
#include<set>
#include<sstream>
#include<stack>
using namespace std;
#define MAX 3410
typedef long long LL;
const double pi=3.141592653589793;
const int INF=1e9;
const double inf=1e20;
const double eps=1e-6;
//高精度加法
string add(string str1,string str2)
{
string str;

int len1=str1.length();
int len2=str2.length();
//前面补0，弄成长度相同
if(len1<len2)
{
for(int i=1;i<=len2-len1;i++)
str1="0"+str1;
}
else
{
for(int i=1;i<=len1-len2;i++)
str2="0"+str2;
}
len1=str1.length();
int cf=0;
int temp;
for(int i=len1-1;i>=0;i--)
{
temp=str1[i]-'0'+str2[i]-'0'+cf;
cf=temp/10;
temp%=10;
str=char(temp+'0')+str;
}
if(cf!=0)  str=char(cf+'0')+str;
return str;
}
//高精度乘法
string mul(string str1,string str2)
{
string str;
int len1=str1.length();
int len2=str2.length();
string tempstr;
for(int i=len2-1;i>=0;i--)
{
tempstr="";
int temp=str2[i]-'0';
int t=0;
int cf=0;
if(temp!=0)
{
for(int j=1;j<=len2-1-i;j++)
tempstr+="0";
for(int j=len1-1;j>=0;j--)
{
t=(temp*(str1[j]-'0')+cf)%10;
cf=(temp*(str1[j]-'0')+cf)/10;
tempstr=char(t+'0')+tempstr;
}
if(cf!=0) tempstr=char(cf+'0')+tempstr;
}
str=add(str,tempstr);
}
str.erase(0,str.find_first_not_of('0'));
if(str.empty()) str="0";
return str;
}
int main(){
string s;
int n,flag;
while(cin>>s>>n){   //s^n
flag=0;
string s1,s2,s3,s4;
int len=s.size();
for(int i=0;i<len;i++){
if(s[i]=='.'){
flag=1;
continue;
}
if(!flag) s1+=s[i];
if(flag) s2+=s[i];
}
int len1=s2.size();
len1=len1*n;
s3=s1+s2;
s4=s3;
for(int i=0;i<n-1;i++){
s4=mul(s4, s3);
}
int len2=s4.size();
string s5,s6,s7;
if(len2>=len1){
for(int i=len2-1;i>=len2-len1;i--) s5=s4[i]+s5;
for(int i=len2-len1-1;i>=0;i--) s6=s4[i]+s6;
}
else{
for(int i=len2-1;i>=0;i--) s5=s4[i]+s5;
for(int i=0;i<len1-len2;i++) s5='0'+s5;
}
s6.erase(0,s6.find_first_not_of('0'));
int len3=s5.size();
int f=0;
for(int i=len3-1;i>=0;i--){
if(!f&&s5[i]=='0') continue;
if(s5[i]!='0') f=1;
if(f) s7=s5[i]+s7;
}
if(s7.empty()) cout<<s6<<endl;
else cout<<s6<<'.'<<s7<<endl;
//------------------------------//
int ans=0;
for(int i=0;i<s6.size();i++)
{
ans+=s6[i]-'0';
}
cout<<ans<<endl;
}
return 0;
}