写代码将三个整数数按从大到小输出
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int main()
{
	int a = 0;
	int b = 0;
	int c = 0;
	int t = 0;
	scanf("%d %d %d", &a, &b, &c);
	if (a < b)
	{
		t = a;
		a = b;
		b = t;
	}
	if (a < c)
	{
		t = a;
		a = c;
		c = t;
	}
	if (b < c)
	{
		t = b;
		b = c;
		c = t;
	}
	printf("%d %d %d\n", a, b, c);

	return 0;
}
打印3的倍数的数
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int main()
{
    int a = 0;
    int b = 0;
    for(int i = 1;i <= 100; i++)
    {
        if(i % 3 == 0)
        {
            printf("%d ",i);
        }
    }
    return 0;
}
最大公约数
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int main()
{
    int a = 0;
    int b = 0;
    int c = 0;
    scanf("%d %d", &a, &b);
    if(a < b)//确保 a<=b
    {
        c = a;
        a = b;
        b = c;
    }
    while(b != 0)
    {
        c = a % b;
        a = b;
        b = c;
    }
    printf("%d", a);
    
    return 0;
}

打印闰年

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int main()
{
	for (int a = 1000; a <= 2000; a++)
	{
		if (a % 4 == 0 && a % 100 != 0 || a % 400 == 0)
			printf("%d ", a);
	}
	return 0;
}

打印素数

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int main()
{
	int a = 0;
	int i = 0;
	for (a = 100; a <= 200; a++)
	{
		for (i = 2; i < a; i++)
		{
			if (a % i == 0)
			{
				break;
			}
		}
		if(a==i)
		{
			printf("%d ", a);
		}
	}
	return 0;
}

数9的个数

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int main()
{
	int a;
	int i = 0;
	for (a = 0; a <= 100; a++)
	{
		if (a % 10 == 9)
		{
			i++;
		}
		if (a / 10 == 9)
		{
			i++;
		}
	}
	printf("%d", i);
	return 0;
}

分数求和

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int main()
{
	double a = 0.0, b = 0.0,c = 0.0;
	for (int i = 1; i <= 100; i += 2)
	{
		a = a + (1.0) / i;
	}
	for (int i = 2; i <= 100; i += 2)
	{
		b = b + (1.0) / i;
	}
	c = a - b;
	printf("%lf", c);
	return 0;
}

求最大值

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