54行代码（入门版）

#include<bits/stdc++.h>
using namespace std;

int main(){
    int a,b[105]={};
    cin>>a;
    for(int i=a;i>=0;i--){
        cin>>b[i];
    }
    for(int i=a;i>=0;i--){
        if(b[i]!=0&&i>1&&i!=a){
            if(b[i]<0){
                if(b[i]!=-1){
                    cout<<b[i]<<"x";
                }else{
                    cout<<"-x";
                }
            }else if(b[i]>0){
                if(b[i]!=1){
                    cout<<"+"<<b[i]<<"x";
                }else{
                    cout<<"+x";
                }
            }
            cout<<"^"<<i;
        }else if(b[i]!=0&&i!=a){
            if(b[i]<0){
                if(i==1&&b[i]==-1){
                    cout<<"-";
                }else{
                    cout<<b[i];
                }
            }else{
                if(i==1&&b[i]==1){
                    cout<<"+";
                }else{
                    cout<<"+"<<b[i];
                }
            }
            if(i==1){
                cout<<"x";
            }
        }else if(b[i]!=0){
            if(b[i]==1){
                cout<<"x"<<"^"<<a;
            }else if(b[i]==-1){
                cout<<"-x"<<"^"<<a;
            }else{
                cout<<b[i]<<"x"<<"^"<<a;
            }
        }
    }
    return 0;
}