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…
Codeforce 1000 D. Yet Another Problem On a Subsequence 解析(DP) 今天我們來看看CF1000D 題目連結 題目 略,請直接看原題 前言 這題提供了我一種實用的算\(C_m^n\)的方法 @copyright petjelinux 版權所有 觀看更多正版原始文章請至petjelinux的blog 想法 考慮\(dp[i]\)為考慮到\(i\)位置為止的所以\(subsequence\)數量\(+1\)(一個都不選),解答就是\(dp[n]-…
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…
http://poj.org/problem?id=1458 用dp[i][j]表示处理到第1个字符的第i个,第二个字符的第j个时的最长LCS. 1.如果str[i] == sub[j],那么LCS长度就可以+1,是从dp[i - 1][j - 1] + 1,因为是同时捂住这两个相同的字符,看看前面的有多少匹配,+1后就是最大长度. 2.如果不同,那怎么办? 长度是肯定不能增加的了. 可以考虑下删除str[i] 就是dp[i - 1][j]是多少,因为可能i - 1匹配了第j个.也可能删除sub…
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 sequences [3,7,8],[2,5,4,1],[0][3,7,8],[2,5,4,1],[0] — are…
Common Subsequence Time Limit: 2 Sec  Memory Limit: 64 MBSubmit: 951  Solved: 374 Description A subsequence of a given sequence is the given sequence with some elements (possible none) left out. Given a sequence X = <X1, x2, ..., xm>another sequence…
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…
Problem C: Longest Common Subsequence Sequence 1: Sequence 2: Given two sequences of characters, print the length of the longest common subsequence of both sequences. For example, the longest common subsequence of the following two sequences: abcdgh…
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…
题目链接: Ordered Subsequence Time Limit: 4000/2000 MS (Java/Others)     Memory Limit: 32768/32768 K (Java/Others) Problem Description   A numeric sequence of ai is ordered if a1<a2<……<aN. Let the subsequence of the given numeric sequence (a1, a2,……,…
题目链接:http://poj.org/problem?id=1458 Common Subsequence Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 55099   Accepted: 22973 Description A subsequence of a given sequence is the given sequence with some elements (possible none) left ou…
题目链接:http://poj.org/problem?id=2533 Longest Ordered Subsequence Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 55459   Accepted: 24864 Description A numeric sequence of ai is ordered if a1 < a2 < ... < aN. Let the subsequence of the…
题目链接:http://poj.org/problem?id=2533 描述: A numeric sequence of ai is ordered if a1 < a2 < ... < aN. Let the subsequence of the given numeric sequence (a1, a2, ..., aN) be any sequence (ai1, ai2, ..., aiK), where 1 <= i1 < i2 < ... < iK…
UVA - 11404 Palindromic Subsequence 题意:一个字符串,删去0个或多个字符,输出字典序最小且最长的回文字符串 不要求路径区间DP都可以做 然而要字典序最小 倒过来求LCS,转移同时维护f[i][j].s为当前状态字典序最小最优解 f[n][n].s的前半部分一定是回文串的前半部分(想想就行了) 当s的长度为奇时要多输出一个(因为这样长度+1,并且字典序保证最小(如axyzb  bzyxa,就是axb|||不全是回文串的原因是后半部分的字典序回文串可能不是最小,多…
E. 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…
题目链接: 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…
Problem F "Folding" Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100002 Description Bill is trying to compactly represent sequences of capital alphabetic characters from 'A' to 'Z' by folding repeating subsequences insid…
这是现场完整做出来的唯一一道题Orz..而且还调了很久的bug.还是太弱了. Problem When you travel, you like to spend time sightseeing in as many cities as possible, but sometimes you might not be able to because you need to catch the bus to the next city. To maximize your travel enjoy…
Problem H. Password Service 题目连接: http://www.codeforces.com/gym/100253 Description Startups are here, startups are there. Startups are everywhere! Polycarp would like to have his own startup, too. His business idea is a password service. Have you not…
题目链接:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3777 Time Limit: 2 Seconds      Memory Limit: 65536 KB The 11th Zhejiang Provincial Collegiate Programming Contest is coming! As a problem setter, Edward is going to arrange the order…
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…
Tree chain problem Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 262    Accepted Submission(s): 59 Problem Description Coco has a tree, whose vertices are conveniently labeled by 1,2,-,n. The…
E. 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…
Simple String Problem Recently, you have found your interest in string theory. Here is an interesting question about strings. You are given a string S of length n consisting of the first k lowercase letters. You are required to find two non-empty sub…
Common Subsequence A subsequence of a given sequence is the given sequence with some elements (possible none) left out. Given a sequence X = < x1, x2, ..., xm > another sequence Z = < z1, z2, ..., zk > is a subsequence of X if there exists a s…
http://acm.ecnu.edu.cn/problem/3261/ 分词 Time limit per test: 1.0 seconds Time limit all tests: 1.0 seconds Memory limit: 256 megabytes 有一句句子因为粘贴的时候出现了一点问题空格全部丢失了.现在给一本字典,每个词都对应这个词出现的频率(每十亿).根据这个频率,我们可以根据下面的公式算出这个词带来的收益 P(word) : P(word)=len2(word)⋅ln…
A. Substring and Subsequence   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 wondered, how many different pairs of "x y" are there, s…
The 11th Zhejiang Provincial Collegiate Programming Contest is coming! As a problem setter, Edward is going to arrange the order of the problems. As we know, the arrangement will have a great effect on the result of the contest. For example, it will…
One Person Game Time Limit: 1 Second      Memory Limit: 32768 KB      Special Judge There is a very simple and interesting one-person game. You have 3 dice, namely Die1, Die2 and Die3. Die1 has K1 faces. Die2 has K2 faces. Die3 has K3 faces. All the…
题目链接 基础的最长公共子序列 #include <bits/stdc++.h> using namespace std; ; char c[maxn],d[maxn]; int dp[maxn][maxn]; int main() { while(scanf("%s%s",c,d)!=EOF) { memset(dp,,sizeof(dp)); int n=strlen(c); int m=strlen(d); ;i<n;i++) ;j<m;j++) if(c…