E - Number Clicker 思路:双向搜索 代码: #include<bits/stdc++.h> using namespace std; #define fi first #define se second #define pi acos(-1.0) #define LL long long //#define mp make_pair #define pb push_back #define ls rt<<1, l, m #define rs rt<<1…

Codeforces 55D Beautiful Number a positive integer number is beautiful if and only if it is divisible by each of its nonzero digits. Input The first line of the input contains the number of cases t (1 ≤ t ≤ 10). Each of the next t lines contains two…

CF995E Number Clicker 题目描述 Allen is playing Number Clicker on his phone. He starts with an integer u u on the screen. Every second, he can press one of 3 buttons. Turn \(u \to u+1 \pmod{p}\). Turn \(u \to u+p-1 \pmod{p}\). Turn \(u \to u^{p-2} \pmod{…

双向bfs  注意数很大  用map来存 然后各种难受....…

链接 大意: 给定模数$p$, 假设当前在$x$, 则可以走到$x+1$, $x+p-1$, $x^{p-2}$ (mod p), 求任意一条从u到v不超过200步的路径 官方题解给了两个做法, 一个是直接双端搜索, 复杂度大概$O(\sqrt PlogP)$ 还有一种方法是求出两条u->1, v->1长度不超过100的路径, 通过随机生成一个数x, 再对$(ux(mod P), u)$做欧几里得算法 操作2相当于减法, 操作三相当于交换 大概写了下双端搜索 #include <iost…

题意:给出u,v,p,对u可以进行三种变化: 1.u=(u+1)%p ; 2.u = (u+p-1)%p;  3.u = 模p下的逆元.问通过几步可以使u变成v,并且给出每一步的操作. 分析:朴素的bfs或dfs会超时或炸栈,考虑用双向bfs头尾同时搜.用map存每个数的访问状态和对应的操作编号,正向搜步长为正,反向搜步长为负.反向搜的时候要注意对应加减操作是反过来的. #include<stdio.h> #include<iostream> #include<cstring…

题目链接:http://codeforces.com/problemset/problem/40/E 妙啊... 因为已经确定的格子数目严格小于了$max(n,m)$,所以至少有一行或者一列是空着的,那么除了这一行或者这一列的格子,其余的格子随意填,只要满足了当且对应的行(列)的积是$-1$就好了,用组合数算一算就好了,剩下的空着的一行或者一列用于收尾,可以发现它当且仅有一种放法. 考虑无解:如果$n+m$为奇数,同时还要注意一下如果$n=1$,或者$m=1$的情况 #include<iostr…

题目链接:http://codeforces.com/problemset/problem/124/A Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing b…

D. Soldier and Number Game time limit per test3 seconds memory limit per test256 megabytes inputstandard input outputstandard output Two soldiers are playing a game. At the beginning first of them chooses a positive integer n and gives it to the seco…

把数位dp写成记忆化搜索的形式,方法很赞,代码量少了很多. 下面为转载内容:  a positive integer number is beautiful if and only if it is divisible by each of its nonzero digits.    问一个区间内[l,r]有多少个Beautiful数字    范围9*10^18        数位统计问题,构造状态也挺难的,我想不出,我的思维局限在用递推去初始化状态,而这里的状态定义也比较难    跟pre的…