int main()
{
	int n = 0;
	printf("请输入n：");
	scanf("%d", &n);
	int i = 0;
	int ret = 1;
	for (i = 1; i <= n; i++)
	{
		ret *= i;
	}
	printf("%d", ret);
	return 0;
}

int main()
{
	int n = 10;
	int i = 0;
	int ret = 1;
	int sum = 0;
	for (i = 1; i <= n; i++)
	{
		ret *= i;
		sum += ret;
	}
	printf("%d", sum);
	return 0;
}

#include<stdio.h>
#include<string.h>
int main()
{
	char arr1[] = "I Love China !!!!!!!";
	char arr2[] = "####################";
	int length = strlen(arr1);
 
	int left = 0;
	int right = length - 1;
 
	while (left < right)
	{
		arr2[left] = arr1[left];
		arr2[right] = arr1[right];
		printf("%s\n", arr2);
		left++;
		right--;
	}
	return 0;
}