答案来喽哈哈

#include <bits/stdc++.h>

using namespace std;

long long n , a;

int main( ) {
	cin >> n;
	
	for (int i = n ; i >= 0 ; i--) {
		cin >> a;
		
		if (a == 0) continue;
		
		if (i == 0) {
			if (a > 0 && n != 0) {
				cout << "+";
			}
			cout << a;
			continue;
		}
		
		if (a > 0 && i != n) cout << "+";//符号
		
		if (a != -1 && a != 1) cout << a;
		else if (a == -1) cout << "-";//系数
		
		if (i == 1) cout << "x";
		else cout << "x^" << i;
	}
	
	return 0;
}