题意:给定一个无穷项的分式,它的和等于π,问π的十六进制表示的小数点后第n位是多少 1 ≤ n ≤ 100000 思路:From https://blog.csdn.net/meopass/article/details/78327614 C++double写起来细节真是烦 #include<cstdio> #include<cstring> #include<string> #include<cmath> #include<iostream>…

题目链接: HDU 7217 题意: 题目给你可以计算 \(π\) 的公式: \(\pi = \sum_{k=0}^{\infty}[\frac{1}{16^k}(\frac{4}{8k+1})-(\frac{2}{8k+4})-(\frac{1}{8k+5})-(\frac{1}{8k+6})]\) 告诉你可以求十六进制下的小数点后 \(π\) 的第 \(n\) 位,而不用计算前 \(n-1\) 项. 十六进制表示下,问你 \(π\) 的小数点后的第 \(n\) 位是多少 $ (1 ≤ n ≤…

题意 已知公式:$\pi=\sum_{k=0}^{\infty}\left[\frac{1}{16^{k}}\left(\frac{4}{8 k+1}-\frac{2}{8 k+4}-\frac{1}{8 k+5}-\frac{1}{8 k+6}\right)\right]$ 求 $\pi$ 的第 $n$ 项. 分析 WIKI上有:π的BBP位抽取算法 这类公式是用来求解一些无理数常数的公式,特点是不需要求解前n-1位也能去算第n位 将公式乘以 $16^n$ 就能将小数点移动到第 $n$ 位.…

题目链接:https://cn.vjudge.net/problem/HDU-6217 题意 已知: \[ \pi = \sum_{k=0}^{\infty }\frac{1}{16^{k}}(\frac{4}{8k+1}-\frac{2}{8k+4}-\frac{1}{8k+5}-\frac{1}{8k+6}) \] 求pi的16进制下小数点后第n位是多少. n<=1e5 思路 要算pi的第n位,首先把pi向前移n位,则个位上就是要求的数. 但是我们很快发现难以计算这个个位数(乘法逆元可能不存…

8201-BBP Formula Time limit: 3.000 seconds In 1995, Simon Plouffe discovered a special summation style for some constants. Two year later, together with the paper of Bailey and Borwien published, this summation style was named as the Bailey-Borwein-P…

A: BBP Formula https://www.cnblogs.com/LzyRapx/p/7802790.html #include <bits/stdc++.h> using namespace std; #define ll long long inline ll qpow(ll x, ll n, ll mod) { ll base = x; ll ans = ; while (n) { ) ans = (ans * base) % mod; base = base * base…

最近做到一个关于杨氏矩阵的题目. UVALive 6625 题目大意是用n以内的数填充杨氏矩阵,要求行严格递增,列不严格递增. 求方案数. 数据范围很小,我直接上爆搜,结果TLE了. 后来发现一位学长用爆搜过了,可能和搜索顺序有点关系,我是按列搜索,学长是按行. 此题的标算应该是状压dp,因为按行是严格递增的,所以可以 按列划分阶段,状态存储这一行用了哪些数即可. 其实这题还可以直接套公式. 行和列都严格递增的杨氏矩阵 方案数是  行严格递增列不严格自增,只能填数1-r的方案数是 参考下面的文章…

UVALive - 4108 SKYLINE Time Limit: 3000MS     64bit IO Format: %lld & %llu Submit Status uDebug Description   The skyline of Singapore as viewed from the Marina Promenade (shown on the left) is one of the iconic scenes of Singapore. Country X would a…

UVALive - 3942 Remember the Word A potentiometer, or potmeter for short, is an electronic device with a variable electric resistance. It has two terminals and some kind of control mechanism (often a dial, a wheel or a slide) with which the resistance…

UVALive - 3942 Remember the Word Neal is very curious about combinatorial problems, and now here comes a problem about words. Know- ing that Ray has a photographic memory and this may not trouble him, Neal gives it to Jiejie. Since Jiejie can’t remem…