WA on#4 90pts求助

rt

#include <bits/stdc++.h>
using namespace std;
const int N=105;
int n;
int a[N];
int main(){
    scanf("%d",&n);
    for(int i=n;i>=0;i--){
        scanf("%d",&a[i]);
    }
    if(n==0)    cout<<a[0];
    else{
        for(int i=n;i>=0;i--){
            if(i==n){
                if(a[i]==0) continue;
                if(a[i]==1){
                    putchar('x');
                    putchar('^');
                    printf("%d",i);
                }
                else if(a[i]==-1){
                    putchar('-');
                    putchar('x');
                    putchar('^');
                    printf("%d",i);
                }
                else{
                    printf("%d",a[i]);
                    putchar('x');
                    putchar('^');
                    printf("%d",i);
                }

            }
            else if(i==1){
                if(a[i]==0) continue;
                if(a[i]<0){
                    if(a[i]==-1){
                        puts("-x");
                    }
                    else{
                        printf("%d",a[i]);
                        printf("x");
                    }
                }
                else{
                    if(a[i]==1) {
                        puts("+");
                        putchar('x');
                    }
                    else{
                        printf("+%d",a[i]);
                        putchar('x');
                    }    
                }
            }
            else if(i==0){
                if(a[i]==0) continue;
                if(a[i]<0){
                    printf("%d",a[i]);
                }
                else{
                    putchar('+');
                    printf("%d",a[i]);
                }
            }
            else{
                if(a[i]==0) continue;
                if(a[i]<0){
                    if(a[i]==-1){
                        printf("-x^%d",i);
                    }
                    else{
                        printf("%dx^%d",a[i],i);
                    }
                }
                else{
                    if(a[i]==1) printf("+x^%d",i);
                    else{
                        printf("+%d",a[i]);
                        putchar('x');
                        putchar('^');
                        printf("%d",i);
                    }

                }
            }
        }
    }
    return 0;
}