$dp$,组合数. $dp[i][j]$表示只用数字$i$,$i+1$,$i+2$......,$9$,凑成长度为$j$的并且数字$i$到$9$符合要求的方案数.只要枚举数字$i$用几个就可以转移了. $dp[i][j] = \sum\limits_{k = a[i]}^n {(dp[i + 1][j - k]} *c[j][k])$,$0$的时候需要特别写一下转移方程,因为$0$不能放在第一位. #include<cstdio> #include<iostream> #inclu…

D. Beautiful numbers time limit per test 4 seconds memory limit per test 256 megabytes input standard input output standard output Volodya is an odd boy and his taste is strange as well. It seems to him that a positive integer number is beautiful if…

来源:http://codeforces.com/problemset/problem/1265/B   B. Beautiful Numbers   You are given a permutation p=[p1,p2,…,pn]p=[p1,p2,…,pn] of integers from 11 to nn . Let's call the number mm (1≤m≤n1≤m≤n ) beautiful, if there exists two indices l,rl,r (1≤l…

D. Numbers time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output One day Anna got the following task at school: to arrange several numbers in a circle so that any two neighboring numbers differs…

C. Page Numbers time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output «Bersoft» company is working on a new version of its most popular text editor - Bord 2010. Bord, like many other text editor…

描述: «Bersoft» company is working on a new version of its most popular text editor — Bord 2010. Bord, like many other text editors, should be able to print out multipage documents. A user keys a sequence of the document page numbers that he wants to p…

pro:给定三个整数L,R,P求[L,R]区间的整数有多少个是以P为最小因子的.L,R,P<2e9; sol: 一: 比较快的做法是,用函数的思想递归. 用solve(N,P)表示求1到N有多少数字多少个的最小因子是P: 1,首先P是合数,或者N<P:solve=0: 2,否则,如果P*P>=N:solve=1: 3,solve=N/P-solve(N/P,i);     2<=i<P 由于P主要分布在sqrt(N),而且N每次log级别减小,所以收缩得很快.具体的复杂度我证…

数位dp的思想就在于递归,记录当前的某一个唯一状态,依次递归下去,要注意唯一. 数位dp常设的状态有当前位置,上一数字,是否具有前导零,是否有限制. 1.CodeForces 55DBeautiful numbers 题目大意:一个数是幸运数当且仅当这个数能整除所有位数,求[a,b]有多少幸运数 10以内的数的最小公倍数是2520,状态为当前位置,模2520的值,出现了哪些数字(状压,1,0删去) #include<iostream> #include<stdio.h> #incl…

[codeforces 55]D. Beautiful numbers 试题描述 Volodya is an odd boy and his taste is strange as well. It seems to him that a positive integer number is beautiful if and only if it is divisible by each of its nonzero digits. We will not argue with this and…

 Phone Numbers Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u Submit Status Practice CodeForces 151B Description Winters are just damn freezing cold in Nvodsk! That's why a group of n friends prefers to take a taxi, ord…