链接: https://vjudge.net/problem/LightOJ-1095 题意: Consider this sequence {1, 2, 3 ... N}, as an initial sequence of first N natural numbers. You can rearrange this sequence in many ways. There will be a total of N! arrangements. You have to calculate t…
1095 - Arrange the Numbers Consider this sequence {1, 2, 3 ... N}, as an initial sequence of first N natural numbers. You can rearrange this sequence in many ways. There will be a total of N! arrangements. You have to calculate the number of arrangem…
给出n,m,k,求1~n中前m个正好有k个在原来位置的种数(i在第i个位置) 做法:容斥,先选出k个放到原来位置,然后剩下m-k个不能放到原来位置的,用0个放到原来位置的,有C(m-k,0)*(n-k)!种 - 1个放原来位置的,有C(m-k,1)*(n-k-1)!种+...-... #include <bits/stdc++.h> using namespace std; typedef long long LL; ; const int INF=0x3f3f3f3f; ; ,T; int…
转载请注明出处: http://www.cnblogs.com/fraud/ ——by fraud Iahub and Permutations Iahub is so happy about inventing bubble sort graphs that he's staying all day long at the office and writing permutations. Iahubina is angry that she is no more import…
A permutation \(p\) of size \(n\) is an array such that every integer from \(1\) to \(n\) occurs exactly once in this array. Let's call a permutation an almost identity permutation iff there exist at least \(n - k\) indices \(i (1 ≤ *i* ≤ n)\) such t…
