HDU-1015-Safecracker

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
string a;
int t;
int v,w,x,y,z;
int vis[20];
int b[6];
int flag;
int cmp(int a,int b)
{
return a>b;
}
void dfs(int k)
{
int i;
if(k==5)
{
if(b[0]-b[1]*b[1]+b[2]*b[2]*b[2]-b[3]*b[3]*b[3]*b[3]+b[4]*b[4]*b[4]*b[4]*b[4]==t)
{
flag=1;
}
return ;
}
for(i=0;i<a.size();i++)
{
if(!vis[i]&&!flag)
{
vis[i]=1;
b[k]=a[i]-'A'+1;
dfs(k+1);
vis[i]=0;
}
}
return;
}
int main()
{
int i;
while(cin>>t>>a,t!=0||a!="END")
{
flag=0;
memset(vis,0,sizeof(vis));
sort(a.begin(),a.end(),cmp);
dfs(0);
if(flag)
{
for(i=0;i<5;i++)
printf("%c",b[i]-1+'A');
cout<<endl;
}
else
cout<<"no solution"<<endl;
}
return 0;
}