题目连接:Harvest of Apples 题意:给出一个n和m,求C(0,n)+C(1,n)+.....+C(m,n).(样例组数为1e5) 题解:首先先把阶乘和逆元预处理出来,这样就可O(1)将C(m,n)求出来了.但这样还是会超时,所以接下来要分块,每隔500个处理出C(1~m,n)的结果.然后还要知道一个性质 C(a,b) = ∑C(t1,x)*C(t2,y)  (x+y<=b),这样我们就可以将给出的m和n分为两个组,其中一个组中元素的个数为500的倍数.然后我们对于另一个组枚举可能…

题意: T次询问,每次给出n,m.求sigma(k:0->m)C(n, k). 题解: 用离线莫队来做. 令S(n,m) = sigma(k:0->m)C(n, k). S(n+1, m) = 2S(n, m) - C(n, m)   S(n-1, m) = (S(n, m) + C(n-1, m)) / 2 S(n, m+1) = S(n, m) + C(n, m+1)   S(n, m-1) = S(n, m) - C(n, m) #include <bits/stdc++.h>…

2018 Multi-University Training Contest 4 6333.Problem B. Harvest of Apples 题意很好懂,就是组合数求和. 官方题解: 我来叨叨一些东西. 这题肯定不能一个一个遍历求和,这样就上天了... 解释一下官方题解的意思. 为什么 sum(n,m)=2*sum(n-1,m)-c(n-1,m). 因为c(n,m)=c(n-1,m)+c(n-1,m-1),至于为什么成立,不懂的百度一下组合数和杨辉三角吧... sum(n,m)=c(n,…

Problem B. Harvest of Apples Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 3088    Accepted Submission(s): 1201 Problem Description There are n apples on a tree, numbered from 1 to n.Count t…

Problem B. Harvest of Apples Time Limit: / MS (Java/Others) Memory Limit: / K (Java/Others) Total Submission(s): Accepted Submission(s): Problem Description There are n apples on a tree, numbered to n. Count the number of ways to pick at most m apple…

任意门:http://acm.hdu.edu.cn/showproblem.php?pid=6333 Problem B. Harvest of Apples Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 4043    Accepted Submission(s): 1560 Problem Description There a…

问题 B: Harvest of Apples 时间限制: 1 Sec  内存限制: 128 MB提交: 18  解决: 11[提交] [状态] [讨论版] [命题人:admin] 题目描述 There are n apples on a tree, numbered from 1 to n.Count the number of ways to pick at most m apples. 输入 The first line of the input contains an integer T…

Problem B. Harvest of Apples Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 2397    Accepted Submission(s): 934 Problem Description There are n apples on a tree, numbered from 1 to n.Count th…

hdu6333 Problem B. Harvest of Apples 题目传送门 题意: 求(0,n)~(m,n)组合数之和 题解: C(n,m)=C(n-1,m-1)+C(n-1,m)    设 S(n,m)=C(n,0)+C(n,1)+C(n,2)+...+C(n,m) 然后将S(n,m) 通过 第一个公式 拆项 最后化简 变为 S(n,m)=2*S(n-1,m)-C(n-1,m); 即: 所以可以离线用莫队算法 参考博客:链接1.链接2 代码: #include <bits/stdc+…

Problem Description There are n apples on a tree, numbered from 1 to n.Count the number of ways to pick at most m apples.   Input The first line of the input contains an integer T (1≤T≤105) denoting the number of test cases.Each test case consists of…