题解 | 多项式输出

#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using ld = long double;
using PII=pair<ll,ll>;
using PIII=pair<int,pair<int,int>>;
const ld ESP = 1e-10;
const ld PI = acosl(-1);
const int N=1e5+10;
const int M=2e5+10;
// const int mod = 1000000007;
const int mod = 998244353;
//随机化
random_device rd;
mt19937 gen(rd());
uniform_int_distribution<> dis(1, 1000000000);


void solve(){
    int n;
    cin>>n;
    int c[n+1];
    for(int i=0;i<=n;i++){
        cin>>c[i];
    }
    int f=0;
    for(int i=0;i<=n;i++){
        if(c[i]==0)continue;
        else{
            if(i>=n-1){
                if(i==n){
                    if(f==0){
                        cout<<c[i];
                        f=1;
                    }else{
                        if(c[i]>0)cout<<"+"<<c[i];
                        else cout<<c[i];
                    }
                }else{
                    if(f==0){
                        if(c[i]==1){
                            cout<<"x";
                        }else if(c[i]==-1){
                            cout<<"-x";
                        }else{
                            cout<<c[i]<<"x";
                        }
                        f=1;
                    }else{
                        if(c[i]==1){
                            cout<<"+x";
                        }else if(c[i]==-1){
                            cout<<"-x";
                        }else{
                            if(c[i]>0)cout<<"+"<<c[i]<<"x";
                            else cout<<c[i]<<"x";
                        }
                    }
                }
                
            }else{
                if(f==0){
                    if(c[i]==1){
                        cout<<"x^"<<n-i;
                    }else if(c[i]==-1){
                        cout<<"-x^"<<n-i;
                    }else{
                        cout<<c[i]<<"x^"<<n-i;
                    }
                    f=1;
                }else{
                    if(c[i]==1){
                        cout<<"+x^"<<n-i;
                    }else if(c[i]==-1){
                        cout<<"-x^"<<n-i;
                    }else{
                        if(c[i]>0)cout<<"+"<<c[i]<<"x^"<<n-i;
                        else cout<<c[i]<<"x^"<<n-i;
                    }
                }
            }
        }
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int _=1;
    // cin>>_;
    while(_--){
        solve();
    }
    return 0;
}