PAT-A1103

#include<stdio.h>#include<vector>using namespace std;int n, k, p, max_facsum=-1;vector<int> fac, temp, ans;int get_p(int a){int loop=0, ans=1;while(loop<p){ans=ans*a; loop++;}return ans;}void DFS(int index, int nowk,int sum, int facsum){if(nowk>k || sum>n)return;if(nowk==k && sum==n && facsum>max_facsum){max_facsum=facsum;ans=temp;}if(index>0){temp.push_back(index);DFS(index,nowk+1,sum+fac[index],facsum+index);  //选temp.pop_back();DFS(index-1,nowk,sum,facsum);  //不选}}int main(){int i=0, tt=0;scanf("%d%d%d",&n,&k,&p);while(tt<=n){tt=get_p(i++);fac.push_back(tt);}DFS(fac.size()-1,0,0,0);if(max_facsum==-1)printf("Impossible\n");else {printf("%d = %d^%d",n,ans[0],p);for(i=1;i<ans.size();i++)printf(" + %d^%d",ans[i],p);}return 0;}