从小老师就教导我们，不会做的题就选C，因为选择题选C的概率是最高的。事实上真是如此吗？今天我突发奇想，利用Google做了一个小实验。统计显示，答案选C的题果然是最多的！
Results 1 - 10 of about 364,000 for "这道题选A".
Results 1 - 10 of about 352,000 for "这道题选B".
Results 1 - 10 of about 521,000 for "这道题选C".
Results 1 - 10 of about 254,000 for "这道题选D".
Results 1 - 10 of about 2,140 for "这道题为什么选A".
Results 1 - 10 of about 2,200 for "这道题为什么选B".
Results 1 - 10 of about 2,580 for "这道题为什么选C".
Results 1 - 10 of about 1,350 for "这道题为什么选D".
一个迟到的消息：Google Treasure Hunt 2008已经开始了，这是Google Sydney为了挖掘出新的工程师而精心设置的一个活动。现在已经有两道题目了，在以后几周的时间里Google将陆陆续续地发布更多的题目。第一个答对所有问题的人将成为这次Treasure Hunt的获胜者。
有兴趣的朋友赶快去试一试。
Ben orenstein尝试在Goolge Code Search里输入脏话，在众多的开源软件中找到了一些非常牛B的代码：
gdb-6.4.50.20060515:/* OK, now set up the filehdr... */
/* We will NOT put a fucking timestamp in the header here. Every time you
put it back, I will come in and take it out again. I’m sorry. This
field does not belong here. We fill it with a 0 so it compares the
same but is not a reasonable time. — gnu@cygnus.com */
Siesta-0.66: # This job would be great if it wasn’t for the fucking customers.
CGI-FormBuilder-3.0202: # Get field from radio buttons or checkboxes
# Must cycle through all again to see which is checked. yeesh.
# However, this only works if there are MULTIPLE checkboxes!
# The fucking JS DOM *changes* based on one or multiple boxes!?!?!
# Damn damn damn I hate the JavaScript DOM so damn much!!!!!!
DJabberd-0.81: # Trillian, again, is fucking stupid and crashes on just
# about anything its homemade XML parser doesn’t like.
gift-0.11.5:void list_lock_insert_sorted (ListLock *lock, CompareFunc func, void *data)
{
if (lock->locked)
{
/* TODO: this is obviously not right ... this whole fucking module
* sucks anyway */
list_lock_prepend (lock, data);
return;
}
lock->list = list_insert_sorted (lock->list, func, data);
}
bh-asia-03-grugq: /* if we get here, there are massive fucking problems, for a start
* our stack is fucked up, and we can’t return(). Just crash out. */
trunk: /* FIXME: please god, when will the hurting stop? Thus function is so
fucking broken it’s not even funny. */
SQL-Abstract-1.20: # Note to self: I have no idea what this does anymore
# It looks like a cool fucking segment of code though!
# I just wish I remembered writing it… :-\
mendax_linux:for(i = 0 ; i < pktcount; i++) {
from.sin_port = htons(ntohs(from.sin_port) + 1);
pktlen = gen_tcp_pak(&pak, &from, dst, ip_id++,
seq_num, 0L, 0, flags);
seq_num += 64000;
/* don't fire dem packets too fucking fast */
usleep(1000);
send_pak((char *) &pak, pktlen, ether);
putchar('.');
}
SugarOS-for-Microsoft-Full-4.5.0h: /* Outlook can’t fucking follow RFC if someone PAID them to do it…
oh wait, someone paid them NOT to do it. */
AfterStep-2.2.5: /* No we fucking don’t! DB entries should be stored in the same order
as they are in the file ! I can’t belive I was so fucking stupid ! */
gallery-2.0.4/modules/core/classes/GalleryStorage:else if ($affectedRows > 1) {
/* Holy shit, we just updated more than one row! What do we do now? */
return GalleryStatus::error(ERROR_STORAGE_FAILURE, __FILE__, __LINE__,
"$query (" . implode('|', $data) . ") $affectedRows");
}
linux-2.4.34.1/arch/sparc/lib/checksum.S: /* Sun, you just can’t beat me, you just can’t. Stop trying,
* give up. I’m serious, I am going to kick the living shit
* out of you, game over, lights out. */
linux-2.6.1/arch/mips/kernel/sysirix.c: /* 2,191 lines of complete and utter shit coming up… */
nfs-utils-1.1.0/utils/statd/misc.c: if (!(ptr = malloc (size)))
/* SHIT! SHIT! SHIT! */
die (”malloc failed”);
dada-2_10_12: # code below replaces code above - any problems?
# yeah, it doesn’t fucking work.
这个可能比较火星，很多人可能已经知道了这个彩蛋；但如果你事先不知道这个彩蛋而碰巧遇上了，你能找出触发这个彩蛋的条件吗？刚才打开iGoogle，发现一件神奇的事件：我的iGoogle主题的顶部图片上居然出现了一个圆周率π──天上的星星排列出来的形状。我立即想到这是iGoogle的一个彩蛋，但我却不知道是什么东西触发了这个彩蛋。仔细想了一下后，突然恍然大悟，这个触发条件确实符合Google的Geek精神。把当时的截屏放出来给大家看一看，如果你还不曾听说过这个彩蛋，你完全可以通过这个截屏找出这个彩蛋的触发条件。继续看下去前不妨先来找找看~~
图上显示截屏的时间是11点15分。中国是东八区，比标准时间早8小时，因此国际标准时间是3点15分。考虑到本机时间准确性、截屏时间稍晚等原因，很容易想到iGoogle页面的实际生成时间是3点14分。也就是说，当国际标准时间恰为3:14时，iGoogle将会出现彩蛋。
图片地址：http://www.google.com/ig/images/skins/sweetdreams/3.14am/header_bg.jpg
了解更多：http://www.gseeker.com/50226711/googleaeaeeceee_66197.php
看看下面两道题，它的解答非常简单，即使没学过信息学的人也可以想到答案。你能在多短的时间内想出问题的算法来？一小时？一分钟？一秒钟？
1. 给你一个长度为N的链表。N很大，但你不知道N有多大。你的任务是从这N个元素中随机取出k个元素。你只能遍历这个链表一次。你的算法必须保证取出的元素恰好有k个，且它们是完全随机的（出现概率均等）。
2. 给你一个数组A[1..n]，请你在O(n)的时间里构造一个新的数组B[1..n]，使得B[i]=A[1]*A[2]*...*A[n]/A[i]。你不能使用除法运算。
Solution:
1. 遍历链表，给每个元素赋一个0到1之间的随机数作为权重（像Treap一样），最后取出权重最大的k个元素。你可以用一个堆来维护当前最大的k个数。
2. 从前往后扫一遍，然后从后往前再扫一遍。也就是说，线性时间构造两个新数组，P[i]=A[1]*A[2]*...*A[i]，Q[i]=A[n]*A[n-1]*...*A[i]。于是，B[i]=P[i-1]*Q[i+1]。
突然想到，给别人(MM?)介绍信息学时，用这两道题当例子挺合适的。
Matrix67 |
2009-12-15 18:53 | 
