题解 | #圣诞树#

#include <stdio.h>

int main() {
    int i, j, a;
    int count = 0;
    scanf("%d", &a);
    for (i = 1; i <= 3 * a; i++) {
        for (j = 0; j < 3 * a - i; j++) {
            printf(" ");
        }
        count = i % 3;
        for (j = 0; j <= ((i-1) / 3); j++) {
            switch (count)
            {
            case 1:
                printf("*     "); break;
            case 2:
                printf("* *   "); break;
            case 0:
                printf("* * * "); break;
            }
        }
        putchar('\n');
    }
    for (i = 0; i < a; i++) {
        for (j = 1; j <= 3 * a - 1; j++) {
            printf(" ");
        }
        printf("*\n");
    }
    return 0;
}