@楼下不用这么长 看我的

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+5,INF=0x3f3f3f3f;
typedef long long LL;
int n,a[N],sum; 
int main(){
	cin>>n;
	sum = n;
	for(int i=1;i<=n+1;i++)cin>>a[i];
	for(int i=1;i<=n+1;i++){
		if(a[i]>0){
			if(i!=1)printf("+");
			if(a[i]!=1)printf("%d",a[i]);
			else if(sum==0)printf("1");
		}else if(a[i]<0){
			if(a[i]==-1){
				if(sum!=0)printf("-");
				else printf("-1");
			}
			else printf("%d",a[i]);
		}
		if(a[i]!=0){
			if(sum>1)printf("x^%d",sum);
			else if(sum==1)printf("x");
		}
		sum--;
	}
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,a[10002],i,j,k;
	cin>>n;
	k=n;
	for(i=1;i<=n+1;i++){
		cin>>a[i];
	}
	if(a[1]!=0){
		if(a[1]==1){
			cout<<"x"<<"^"<<k;
		}
		if(a[1]==-1){
			cout<<"-x"<<"^"<<k;
		}
		else if(a[1]!=0&&a[1]!=1&&a[1]!=-1){
			cout<<a[1]<<"x"<<"^"<<k;
		}
	}
	k--;
	for(i=2;i<=n;i++){
		if(a[i]>0&&k>1){
			if(a[i]==1){
				cout<<"+x"<<"^"<<k;
			}
			else{
				cout<<"+"<<a[i]<<"x"<<"^"<<k;
			}
			k--;
		}
		else if(a[i]>0&&k==1){
			if(a[i]==1){
				cout<<"+x";
			}
			else{
				cout<<"+"<<a[i]<<"x";
			}
			k--;
		}
		else if(a[i]<0&&k>1){
			if(a[i]==-1){
				cout<<"-x"<<"^"<<k;
			}
			else{
				cout<<a[i]<<"x"<<"^"<<k;
			}
			k--;
		}
		else if(a[i]<0&&k==1){
			if(a[i]==-1){
				cout<<"-x";
			}
			else{
				cout<<a[i]<<"x";
			}
			k--;
		}
		else{
			k--;
		}
	}
	if(a[n+1]>0){
		cout<<"+"<<a[n+1];
	}
	else if(a[n+1]<0){
		cout<<a[n+1];
	}
	return 0;
}