题解 | 圣诞树

#include <stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    int a = 3*n;
    for(int i = 1;i<=n;i++){
        for(int m =1 ;m<=a-1;m++){
            printf(" ");
        }  
        for(int n = 1;n <= i;n++){
            printf("*     ");
        }
        printf("\n");

        for(int m =1 ;m<=a-2;m++){
            printf(" ");
        }  
        for(int n = 1;n <= i;n++){
            printf("* *   ");
        }
        printf("\n");

        for(int m =1 ;m<=a-3;m++){
            printf(" ");
        }  
        for(int n = 1;n <= i;n++){
            printf("* * * ");
        }
        printf("\n");
        a -= 3;  //下一层空格数少三
    }
    for(int i = 1;i<=n;i++){
        for(int j = 1;j<3*n;j++){
            printf(" ");
        }
        printf("*\n");
    }

    return 0;
}