题面 解析 我们设\(f[i]\)表示\(k\)次操作后第一个数在第\(i\)个位置上加了多少次, 而其它的数也可以类推, 第\(i\)个数在第\(j\)个位置加的次数就是\(f[j-i+1]\). 通过找规律手玩样例后可以发现, \(f[i]=C_{i+k-2}^{i-1}\). (然而并不知道为什么) 最后对每个位置统计贡献就行了. code: #include <iostream> #include <cstdio> #include <cstring> #def…

开始想的是O(n2logk)的算法但是显然会tle.看了解题报告然后就打表找起规律来.嘛是组合数嘛.时间复杂度是O(nlogn+n2)的 #include<cstdio> #include<cstring> #include<cctype> #include<algorithm> using namespace std; #define rep(i,s,t) for(int i=s;i<=t;i++) #define dwn(i,s,t) for(in…

Non-negative Partial Sums Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 2622    Accepted Submission(s): 860 Problem Description You are given a sequence of n numbers a0,..., an-1. A cyclic shi…

考试时候遇到这种题只会找规律 You've got an array a, consisting of n integers. The array elements are indexed from 1 to n. Let's determine a two step operation like that: First we build by the array a an array s of partial sums, consisting of n elements. Element nu…

Partial Sums 题解: 一个数列多次前缀和之后, 对于第i个数来说他的答案就是 ; i <= n; ++i){ ; j <= i; ++j){ b[i] = (b[i] + 1ll * a[j] * C(k-+j-i,j-i)) % mod; } } 唯一注意的就是这个k会到1e9. 观察可能,其实我们最多也就用了n个组合数, 并且这个C(n, m) 的 m 足够小. 所以我们可以根据定义先把这几个组合数先预处理出来. 代码: #include<bits/stdc++.h>…

Non-negative Partial Sums Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 1420    Accepted Submission(s): 544 Problem Description You are given a sequence of n numbers a0,..., an-1. A cyclic shi…

Description Given a series of n numbers a1, a2, ..., an, the partial sum of the numbers is defined as the sum of ai, ai+1, ..., aj. You are supposed to calculate how many partial sums of a given series of numbers could be divided evenly by a given nu…

1161 Partial Sums  题目来源: CodeForces 基准时间限制:2 秒 空间限制:131072 KB 分值: 80 难度:5级算法题  收藏  取消关注 给出一个数组A,经过一次处理,生成一个数组S,数组S中的每个值相当于数组A的累加,比如:A = {1 3 5 6} => S = {1 4 9 15}.如果对生成的数组S再进行一次累加操作,{1 4 9 15} => {1 5 14 29},现在给出数组A,问进行K次操作后的结果.(每次累加后的结果 mod 10^9 +…

ACM思维题训练集合 You've got an array a, consisting of n integers. The array elements are indexed from 1 to n. Let's determine a two step operation like that: First we build by the array a an array s of partial sums, consisting of n elements. Element number…

HDU 4193 题意:给n个数字组成的序列(n <= 10^6).求该序列的循环同构序列中,有多少个序列的随意前i项和均大于或等于0. 思路: 这题看到数据规模认为仅仅能用最多O(nlogn)的算法.然后想到了之前刚做过的有关最小表示法的题.但还没证明出一个做这题有效的算法出来. 后来看过题解.发现用的最多的方法是单调队列,然而我对这个知识点知之甚少orz /*科普君:from单调队列 单调队列是指:队列中元素之间的关系具有单调性.并且,队首和队尾都能够进行出队操作.仅仅有队尾能够进行入队操作…