题目链接:http://codeforces.com/contest/597/problem/C 给你n和数(1~n各不同),问你长为k+1的上升自序列有多少. dp[i][j] 表示末尾数字为i 长度为j的上升子序列个数,但是dp数组是在树状数组的update函数中进行更新. update(i, val, j)函数表示在i的位置加上val,更新dp[i][j]. sum(i, j)就是求出末尾数字小于等于i 且长度为j的子序列有多少个. //#pragma comment(linker, "/…

题目大意就是说帮你给出一个序列a,让你求出它的非递减序列有多少个. 设dp[i]表示以a[i]结尾的非递减子序列的个数,由题意我们可以写出状态转移方程: dp[i] = sum{dp[j] | 1<=j<i && a[j] <= a[i]} + 1. 这样一来这里面所有的dp[]值的和就是最后的结果. 但是这个状态转移方程很明显复杂度是O(n^2),但是n可以达到100000,很明显会超时.既然是求前导和,很明显我们就应该可以想到用树状数组(虽然我怎么也不可能想到==!)…

Sereja has a sequence that consists of n positive integers, a1, a2, ..., an. First Sereja took a piece of squared paper and wrote all distinct non-empty non-decreasing subsequences of sequence a. Then for each sequence written on the squared paper, S…

Find the nondecreasing subsequences Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1844    Accepted Submission(s): 677 Problem Description How many nondecreasing subsequences can you find in t…

Increasing Speed Limits Time Limit: 2000/10000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 481    Accepted Submission(s): 245 Problem Description You were driving along a highway when you got caught by the road p…

Ordered Subsequence Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 464    Accepted Submission(s): 216 Problem Description A numeric sequence of ai is ordered if a1<a2<……<aN. Let the subsequ…

题目链接:http://codeforces.com/contest/597/problem/C 思路:dp[i][j]表示长度为i,以j结尾的上升子序列,则有dp[i][j]= ∑dp[i-1][k](1<=k<j),由于要求前缀和,可以用树状数组优化 #include<bits/stdc++.h> #define lowbit(x) x&(-x) typedef long long ll; const int N=1e5+3; ll dp[12][N]; using n…

题意:给你一个字符串和m个询问,问你l,r这个区间内出现过多少字串. 连接:http://acm.hdu.edu.cn/showproblem.php?pid=4622 网上也有用后缀数组搞得. 思路(虎哥):用字典树把每一个字符串对应成一个整数 相同的字符串对应到相同的整数上 把所用的串对应的整数放在一个数组里 比如书字符串s[l...r]对应的整数是 k 那么二维数组 [l][r] 就等于k 假设一个对应好的二维数组  左下角是原点 3     4     5     2 2     3  …

序列计数 Time Limit: 4500/4000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 348    Accepted Submission(s): 117 Problem Description 度度熊了解到,1,2,…,n 的排列一共有 n!=n×(n−1)×⋯×1 个.现在度度熊从所有排列中等概率随机选出一个排列 p1,p2,…,pn,你需要对 k=1,2,…

题目链接: Codeforces261D 题目大意:$k$次询问,每次给出一个长度为$n$的序列$b$及$b$中的最大值$maxb$,构造出序列$a$为$t$个序列$b$连接而成,求$a$的最长上升子序列.$n,maxb\le10^5,maxb*n\le2*10^7,t\le10^9$. 设$b$中不同数的个数为$sum$.如果$sum\le t$,那么答案就是$sum$(只需要从第$i$个序列$b$中取第$i$小的数即可).现在只需要考虑$t<sum$的情况,因为$sum\le maxb$,所…