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CF908D New Year and Arbitrary Arrangement 题解

\(0.\) 前言 有一天 \(Au\) 爷讲期望都见到了此题,通过写题解来加深理解。 \(1.\) 题意 将初始为空的序列的末尾给定概率添加 \(a\) 或 \(b\),当至少有 \(k\) 对 \(ab\) 时停止(注意是“对”,中间可以间隔字符),求 \(ab\) 期望对数。 \(2.\) 思路 通过查看标签 通过阅读题面我们容易发现

526. Beautiful Arrangement

package LeetCode_526 /** * 526. Beautiful Arrangement * https://leetcode.com/problems/beautiful-arrangement/ * Suppose you have n integers labeled 1 through n. * A permutation of those n integers perm (1-indexed) is considered a beautiful arrangement

[GYM102900H]Rice Arrangement

VI.[GYM102900H]Rice Arrangement 首先,考虑最终匹配上的人-饭对中,有两对是 \((a_{i1},b_{j1})\),\((a_{i2},b_{j2})\)(此处的 \(a,b\) 都是原本圆桌上坐标)。假如它们呈包含关系,则我们一定可以交换两碗饭使得它们变成相交关系,且两对所需旋转距离都不增加,也即答案一定不更劣。 我们将

CF908D New Year and Arbitrary Arrangement

LXII.CF908D New Year and Arbitrary Arrangement 思路: 期望题果然还是恶心呀…… 我们设\(f[i][j]\)表示当串中有\(i\)个a和\(j\)个ab时的方案数。为了方便,设\(A=\dfrac{P_a}{P_a+P_b},B=\dfrac{P_b}{P_a+P_b}\)。 显然,可以这样转移: \(f[i][j]=f[i+1][j]*A+f[i][i+j]*B\) 因为,如

0526. Beautiful Arrangement (M)

Beautiful Arrangement (M) 题目 Suppose you have n integers from 1 to n. We define a beautiful arrangement as an array that is constructed by these n numbers successfully if one of the following is true for the ith position (1 <= i <= n) in this array:

Instrction Arrangement UDH 4109 拓扑排序 or 最长路

题目描述 Ali has taken the Computer Organization and Architecture course this term. He learned that there may be dependence between instructions, like WAR (write after read), WAW, RAW. If the distance between two instructions is less than the Safe Distance, i

【关键路径】HDU4109 Instrction Arrangement

Ali has taken the Computer Organization and Architecture course this term. He learned that there may be dependence between instructions, like WAR (write after read), WAW, RAW. If the distance between two instructions is less than the Safe Distance, it

$CF908D\ New\ Year\ and\ Arbitrary\ Arrangement$ 期望$dp$

正解:期望$dp$ 解题报告: 传送门$QwQ$ 阿关于题目里那个形如$ab$的子序列我说下,,,我我我之前$get$了好久$QAQ$.这里子序列的个数的定义是这样儿的,举个$eg$,$aabb$,就有4个形如$ab$的子序列. 然后考虑$dp$?设$f_{i,j}$表示前缀中有$i$个$a$,$j$个$ab$的停止后的期望长度?然后为了

UVA1638 杆子的排列 Pole Arrangement_dp题解

好久没写题解了,今天心情好,,来写一发 这道题是UVA上的题目。众所周知,UVA很卡,所以我实在洛谷上提交的^_^。  //p.s.洛谷真好用 题目戳这里 题意:一个队列中只能放入U和L,问存在连续3个以上U(危险组合)的个数为几个。 思路:这道题中如果直接算有几组存在连续3个以上U的数量, 不是特别的方

526. Beautiful Arrangement

Suppose you have N integers from 1 to N. We define a beautiful arrangement as an array that is constructed by these N numbers successfully if one of the following is true for the ith position (1 <= i <= N) in this array: The number at the ith posit