luogu嘟嘟嘟 这题刚开始特别容易理解错:直接枚举所有\(n + 1\)种情况,然后算哪一种情况合法,再统计答案. 上述思想的问题就在于我们从已知的结果出发,默认这种每一种情况中取出\(q\)个红球,\(p -q\)个蓝球的概率是1,但实际上无法保证取出的红球或是蓝球的数量刚好是这些. 那应该是啥咧,设袋中红球数量是\(i\),则蓝球就是\(n - i\),那么这种取法的概率是\(\frac{C_{i} ^ {q} * C_{n - i} ^ {p - q}}{C_{n} ^ {p}}\),记…

这篇博客主要是用来记自己写代码的时候犯的各种小技巧和低级失误,好提醒自己,从而尽量缩短debug时间. 点分治 1.求每一个子树到重心的距离的函数接口应该是dfs2(v, eg, e[i].w)而不是dfs2(v, now, 0).一方面是子树的父亲是当前的重心,而不是进入这一层点分治的点:另一方面别忘了考虑这条边的贡献. 2-SAT 1.建图一定要考虑对称性,即"如果\(x\)成立,则\(y\)必须成立",那么我们还得考虑如果\(y\)不成立,则\(x\)也不能成立,比如[NOI20…

默认使用软件中心安装node.js,然后参考https://famo.us/install进行安装 1.sudo apt-get install git 2.npm install -g yo grunt-cli bower generator-famous 执行后结果报如下错误 使用npm WARN This failure might be due to the use of legacy binary "node" 经过搜索采取如下方式安装最新node.js ----------…

I can`t help surfing the useless bbs and some other kind of SNS. The time I begin to do it, it costs me a long to stop and do normal work. I just can`t stop. fuck! My boss asks me to report to him every week and forces me to make plun for next week.…

The Famous ICPC Team Again Problem Description   When Mr. B, Mr. G and Mr. M were preparing for the 2012 ACM-ICPC World Final Contest, Mr. B had collected a large set of contest problems for their daily training. When they decided to take training, M…

The Famous Clock 时间限制:1000 ms  |  内存限制:65535 KB 难度:1   描述 Mr. B, Mr. G and Mr. M are now in Warsaw, Poland, for the 2012’s ACM-ICPC World Finals Contest. They’ve decided to take a 5 hours training every day before the contest. Also, they plan to star…

题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=4255 A Famous Grid Description Mr. B has recently discovered the grid named "spiral grid".Construct the grid like the following figure. (The grid is actually infinite. The figure is only a small par…

题目地址: http://blog.csdn.net/sevenmit/article/details/8231994  描述 Mr. B is a famous music composer. One of his most famous work was his set of preludes. These 24 pieces span the 24 musical keys (there are musically distinct 12 scale notes, and each may…

描述 Mr. B is a famous music composer. One of his most famous work was his set of preludes. These 24 pieces span the 24 musical keys (there are musically distinct 12 scale notes, and each may use major or minor tonality). The 12 distinct scale notes ar…

单调栈: 维护一个单调栈 A Famous City Time Limit: 10000/3000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 1671    Accepted Submission(s): 644 Problem Description After Mr. B arrived in Warsaw, he was shocked by the skyscrap…