Let's call a permutation analmost identity permutationiff there exist at leastn - kindicesi(1 ≤ i ≤ n) such thatpi = i. Your task is to count the number ofalmost identitypermutations fo
Let's call a permutation an almost identity permutation iff there exist at least n−kn − k indices i(1≤∗i∗≤n)i(1 ≤ ∗i∗ ≤ n) such that pi=ipi = i. Your task is to count the number of almost identity permutations for given numbers nn and kk....
Codeforces 888D Almost Identity Permutations:错排公式 题目链接:http://codeforces.com/problemset/problem/888/D 题意: 给定n,k,问你有多少种1到n的排列,满足至少有n-k个a[i] == i。 (4 <= n <= 1000, 1 <= k <= 4) 题解: 转换题意: 给定n,k,问你有多少种1到n的排列,满足最多有k个a...
Let's call a permutation analmost identity permutation iff there exist at leastn - kindicesi(1 ≤ i ≤ n) such thatpi = i. Your task is to count the number ofalmost identity permutations for given numbersnandk. Input The first line contains two integersnandk(4 ≤...