题目链接: A. Kyoya and Colored Balls time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labele…

Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labeled from 1 to k. Balls of the same color are indistinguishable. He draws balls from the bag one by one until the bag is empty. He noticed that he…

这个题.比赛的时候一直在往dp的方向想,可是总有一个组合数学的部分没办法求, 纯粹组合数学撸,也想不到办法-- 事实上,非常显然.. 从后往前推,把第k种颜色放在最后一个,剩下的k球.还有C(剩余的位置,k球的总数目-1)种放法 然后讨论第k-1种...推下去就好了 可是当时没想到-- 这里要求组合数.因为比較大.用乘法逆元... 当然直接套lucas也是能够的. ... time limit per test 2 seconds memory limit per test 256 megaby…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labeled from 1 to k. Balls of the same colo…

Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labeled from 1 to k. Balls of the same color are indistinguishable. He draws balls from the bag one by one until the bag is empty. He noticed that he…

题意: 有k种颜色,每种颜色对应a[i]个球,球的总数不超过1000 要求第i种颜色的最后一个球,其后面接着的必须是第i+1种颜色的球 问一共有多少种排法 Sample test(s) input output input output Note In the first sample, we have 2 balls of color 1, 2 balls of color 2, and 1 ball of color 3. The three ways for Kyoya are: 思路:…

题目描述: Kyoya and Colored Balls time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labeled f…

C. Kyoya and Colored Balls Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/554/problem/C Description Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labeled from 1 to k.…

C. Kyoya and Colored Balls Kyoya Ootori has a bag with n colored balls that are colored with k different colors. The colors are labeled from 1 to k. Balls of the same color are indistinguishable. He draws balls from the bag one by one until the bag i…

https://codeforces.com/gym/253910/problem/F F. Kyoya and Colored Balls time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Kyoya Ootori has a bag with n colored balls that are colored with k d…