我用穷举，这个为什么有毛病#include<stdio.h>
int main(){
    int a,b,c,d,e,f,g,h;
    for(a = 1;a <= 765;a++)
        for(b = 1;b <= 765;b++)
            for(c = 1;c <= 765;c++)
                for(d = 1;d <= 765;d++)
                    for(f = 1;f <= 765;f++)
                        for(e = 1;e <= 765;e++)
                            for(g = 1;g <= 765;g++)
                                for(h = 1;h <= 765;h++)
                                    if(b / a == 2 && c / b == 2 && d / c == 2 && e / d == 2 && f /e == 2 && g / f == 2 && h / g == 2)
                                    {
                                        printf("the first floor has %d\n",a);
                                        printf("the eight floor has %d\n",h);
                                    }
}

这个又有什么毛病啊
#include<stdio.h>
int main(){
    int i,sum = 0,n,m = 1;
    while(1)
    {
        n = m;
        sum = m;
        for(i = 1;i <= 8;i++)
        {
            m *= 2;
            sum += m;
        }
        if(sum == 765)
        {
            printf("%d\n",n);
            printf("%d",m);
        }  
        m = n;
        m++;
    }
}

这个我知道哪里错了

你的思路有问题。下一层塔的灯数是上一层塔的两倍。为何你会写成b/a==2，而不是b%a==0

思路:求出顶层的灯数，就可以求出底层的灯数了。
如果顶层有n个，那么总和就是n+2*n+....+2^7*n

    int sum=0;
    int i;
    int m=1;
    for (i = 0; i < 8; i++)
    {
        sum = sum + m;
        m *= 2;
    }

那么塔顶的灯数就是

HightLight=765/sum;

塔底的灯数就是HightLight*2^7

LowLight=HightLight<<7;

[此贴子已经被作者于2018-2-22 00:15编辑过]

b/a==2这个判断条件不对的。b和a都是int型，如果b=5、a=2，b/a==2。可以写成b==2*a;不过你第一个程序实在太夸张了要循环765的8次方次。
 你第二个程序实际上是9层楼，而且是无限循环没有结束。

哦哦，原来如此，感谢

感谢

765÷（2^8-1)=3  3*2^7=384

路过打酱油

/*有一八层灯塔，每层的灯数都是上一层的两倍，共有765盏灯，求最上层与最下层的灯数。*/
#include <stdio.h>
#define AllLight 765
int main()
{
    int sum = 0;
    int layerLight;
    for (int i = 1; i <= AllLight / 2 / 2 / 2 / 2 / 2 / 2 / 2; i++)
    {
        layerLight = i;
        for (int j = 1; j <= 8; j++)
        {
            sum += layerLight;
            layerLight = layerLight * 2;
        }
        if (sum == AllLight)
        {
            printf("第一层：%d\n第八层：%d\n", i, layerLight / 2);
            /*
            layerLight = i;
            for (int j = 1; j <= 8; j++)
            {
                printf("%d\n", layerLight);
                layerLight = layerLight * 2;
            }
            */
            break;
        }
        else sum = 0;
    }
}