In a galaxy far far away there is an ancient game played among the planets. The specialty of the gameis that there is no limitation on the number of players in each team, as long as there is a captain inthe team. (The game is totally strategic, so so…

题意:有n个人,选不少于一个人参加比赛,其中一人当队长,有多少种选择方案. 思路:我们首先C(n,1)选出一人当队长,然后剩下的 n-1 人组合的总数为2^(n-1),这里用快速幂解决 代码: #include <iostream> #define ll long long using namespace std; ; ll qmod(ll a, ll b) { ll ans=; while(b) { ) { ans=(ans*a)%mod; } b=b/; a=(a*a)%mod; } re…

In a galaxy far far awaythere is an ancient game played among the planets. The specialty of the game isthat there is no limitation on the number of players in each team, as long asthere is a captain in the team. (The game is totally strategic, so som…

题目链接 想了一会,应该是跟二项式系数有关系,无奈自己推的式子,构不成二项式的系数. 选1个人Cn1*1,选2个人Cn2*2....这样一搞,以为还要消项什么的... 搜了一下题解,先选队长Cn1,选一个人的时候Cn-1 0,选2个人的时候Cn-1 1这样就构成二项式系数了. 一约,n*2^n-1...最后,还忘了取模,错了好多次.. #include <cstdio> #include <cstring> #include <string> #include <…

看题传送门 题目大意: 有n个人,选一个或者多个人参加比赛,其中一名当队长,如果参赛者相同,队长不同,也算一种方案.求一共有多少种方案. 思路: 排列组合问题. 先选队长有C(n , 1)种 然后从n-1个人中选,但人数不确定,所以应是1个~n-1个人的和. 比如n=1,那么就是C(n , 1)种 n=2 那么就是 C(n , 1)  +  C(n ,1) * C(n-1 , 1) n=3那么就是 C(n , 1)  +  C(n ,1) * C(n-1 , 1)  +  C(n , 1) *…

UVA.11806 Cheerleaders (组合数学 容斥原理 二进制枚举) 题意分析 给出n*m的矩形格子,给出k个点,每个格子里面可以放一个点.现在要求格子的最外围一圈的每行每列,至少要放一个点,并且放在角上的点,同时算那个角所在的行和所在的列.不允许剩下点,求总共的方案数量,结果对1000007取模. 数据范围2 ≤ M,N ≤ 20,K ≤ 500. 考虑到要求组合数目,首先就需要预处理500以内的组合数.正向求解可能有些困难,这样考虑: 不管三七二十一,先求解出所有情况的总和,即C…

n个人里选k个人有C(n, k)中方法,再从里面选一人当队长,有k中方法. 所以答案就是 第一步的变形只要按照组合数公式展开把n提出来即可. #include <cstdio> typedef long long LL; ; LL pow(int p) { LL ans = , ; while(p) { ) ans = (ans * base) % M; p >>= ; base = (base * base) % M; } return ans; } int main() { /…

题意就不多说了这个小规律不算难,比较容易发现,就是让你求一个数n*2^(n-1):很好想只是代码实现起来还是有点小困(简)难(单)滴啦,一个快速幂就OK了: 代码: #include<stdio.h> #define mod 1000000007 #define ll long long ll pow(ll a,ll b) { ll ans=; while(b) { >) ans=ans*a%mod; a=a*a%mod; b/=; } return ans; } int main()…

写的话就是排列组合...但能化简...ΣC(n,i)*C(i,1) 化简为n*2^(n-1) ; #include <iostream> #include <cstdio> #include <sstream> #include <cstring> #include <map> #include <set> #include <vector> #include <stack> #include <queu…

n participants of the competition were split into m teams in some manner so that each team has at least one participant. After the competition each pair of participants from the same team became friends. Your task is to write a program that will find…