题解 | 多项式输出

#include <stdio.h>

int main(void) {
    int n;
    scanf("%d", &n);

    int a[n + 1];
    for (int i = n; i >= 0; i--)
        scanf("%d", &a[i]);

    if (n == 0) {
        printf("%d", a[0]);
        return 0;
    }
    int first = 1;

    if (a[n] != 0) {
        if (a[n] == 1)
            printf("x^%d", n);
        else if (a[n] == -1)
            printf("-x^%d", n);
        else
            printf("%dx^%d", a[n], n);
        first = 0;
    }
    for (int i = n - 1; i >= 2; i--) {
        if (a[i] == 0)
            continue;
        if (a[i] > 0 && !first)
            printf("+");
        if (a[i] == 1)
            printf("x^%d", i);
        else if (a[i] == -1)
            printf("-x^%d", i);
        else printf("%dx^%d", a[i], i);
        first = 0;
    }
    if (a[1] != 0) {
        if (a[1] > 0 && !first)
            printf("+");
        if (a[1] == 1)
            printf("x");
        else if (a[1] == -1)
            printf("-x");
        else printf("%dx", a[1]);
        first = 0;
    }
    if (a[0] != 0) {
        if (a[0] > 0 && !first)
            printf("+");
        printf("%d", a[0]);
    }
    return 0;
}