题面在这里! 好智障的一个dp啊,一段开头的数字相当于下面要跟多少个数,直接滚动数组dp就行了... #include<bits/stdc++.h> #define ll long long using namespace std; const int N=1005,ha=998244353; inline void ADD(int &x,int y){ x+=y; if(x>=ha) x-=ha;} int f[N],n,a[N]; int main(){ scanf(&quo…

C. Sonya and Problem Wihtout a Legend time limit per test 5 seconds memory limit per test 256 megabytes input standard input output standard output Sonya was unable to think of a story for this problem, so here comes the formal description. You are g…

设f[i]是以i为开头的好子序列的个数 那么有$f[i]=\sum\limits_{j=i+a[i]+1}^{N+1}{f[j]*C_{j-i-1}^{a[i]}}$(设f[N+1]=1)就是以i为开头选出一个好子数组的每种情况*再把它拼到后面的一个好子序列的数量 随便用什么方法预处理一下组合数就行了 #include<bits/stdc++.h> #define pa pair<int,int> #define CLR(a,x) memset(a,x,sizeof(a)) usi…

题意:给你一个长度为\(n\)的序列,求一个最长的\({x,x+1,x+2,.....,x+k-1}\)的序列,输出它的长度以及每个数在原序列的位置. 题解:因为这题有个限定条件,最长序列是公差为\(1\)的单增序列,所以其实非常简单. ​ 我们用\(map\)来记录每个元素最后出现的位置,\(dp\)表示当前位置的最长序列,\(last\)表示\(x-1\)的位置. ​ \(dp\)状态有两种更新方式: 1.如果上个元素\((x-1)\)存在,则\(dp[i]=dp[x-1]+1\). ​ 2…

题目链接:http://codeforces.com/contest/283/problem/B 思路: dp[now][flag]表示现在在位置now,flag表示是接下来要做的步骤,然后根据题意记忆化搜索记忆,vis数组标记那些已经访问过的状态. #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #define REP(i, a, b) for (i…

D - Yet Another Problem On a Subsequence CodeForces - 1000D The sequence of integers a1,a2,-,aka1,a2,-,ak is called a good array if a1=k−1a1=k−1 and a1>0a1>0. For example, the sequences [3,−1,44,0],[1,−99][3,−1,44,0],[1,−99] are good arrays, and the…

A. Substring and Subsequence 题目连接: http://codeforces.com/contest/163/problem/A Description One day Polycarpus got hold of two non-empty strings s and t, consisting of lowercase Latin letters. Polycarpus is quite good with strings, so he immediately w…

D. Longest Subsequence 题目连接: http://www.codeforces.com/contest/632/problem/D Description You are given array a with n elements and the number m. Consider some subsequence of a and the value of least common multiple (LCM) of its elements. Denote LCM a…

time limit per test3 seconds memory limit per test256 megabytes inputstandard input outputstandard output A string t is called nice if a string "2017" occurs in t as a subsequence but a string "2016" doesn't occur in t as a subsequence…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output While Mahmoud and Ehab were practicing for IOI, they found a problem which name was Longest common subsequence. They solved it, and then Ehab ch…