题解 100% AC

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,x;cin>>n;
    int cnt=n;
    while(cnt>=0){
        cin>>x;
        if(x!=0){
            if(cnt!=n) if(x>0) cout<<"+";
            if(x<0) cout<<"-";
            if(abs(x)!=1||cnt==0) cout<<abs(x);
            if(cnt>0) cout<<"x";
            if(cnt>1) cout<<"^"<<cnt;
        }
        cnt--;
    }
    return 0;
}