传送门 仔细观察可以发现,如果在一个\(> 1\)的数后面放一个\(> 1\)的数,那么后面的序列也就确定了,所以我们考虑dp出特定长度的序列,然后在后面加上能确定序列的数来贡献答案 为了凑出这样的序列,用来填充的东西是单个的\(1\),或者长度为\(x+1(x>1)\)的 \(x\)加\(x\)个\(1\),所以转移就是\(f_i=\sum_{j=0}^{i-1}[j\ne i-2]f_j\),注意不能加上\(f_{i-2}\),因为\(1\ 1\)会和\(1\)加\(1\)算重 然后…

A.Infinite Sequence time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Consider the infinite sequence of integers: 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5.... The sequence is built in the…

A. Infinite Sequence 题目连接: http://www.codeforces.com/contest/622/problem/A Description Consider the infinite sequence of integers: 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5.... The sequence is built in the following way: at first the number 1 is wr…

题目链接: A. Infinite Sequence time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Vasya likes everything infinite. Now he is studying the properties of a sequence s, such that its first element is…

A. Infinite Sequence time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Consider the infinite sequence of integers: 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5.... The sequence is built in the…

[arc071f]Infinite Sequence(动态规划) 题面 atcoder 洛谷 题解 不难发现如果两个不为\(1\)的数连在一起,那么后面所有数都必须相等. 设\(f[i]\)表示\([i,n]\)的填法数,初值\(f[n]=n,f[n-1]=n*n\) 考虑转移, 首先可以这里填上一个大于\(1\)的数然后后面连续若干个\(1\),这一部分的方案数是\(\sum_{j=i+3}^n f[j]\),这个后缀和记录一下就好了,然而还漏了一部分,即如果\(i+a_i>n\),那么这里的…

A. Infinite Sequence 题目连接: http://www.codeforces.com/contest/675/problem/A Description Vasya likes everything infinite. Now he is studying the properties of a sequence s, such that its first element is equal to a (s1 = a), and the difference between…

A. Infinite Sequence time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Consider the infinite sequence of integers: 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5.... The sequence is built in the…

Problem description Consider the infinite sequence of integers: 1, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 3, 4, 5.... The sequence is built in the following way: at first the number 1 is written out, then the numbers from 1 to 2, then the numbers from 1 to…

Vasya likes everything infinite. Now he is studying the properties of a sequence s, such that its first element is equal to a (s1 = a), and the difference between any two neighbouring elements is equal to c (si - si - 1 = c). In particular, Vasya won…