找规律 2015百度之星资格赛 1001 大搬家

 

题目传送门

 1 /*  2  找规律：题目真心读不懂，排列组合的题目  3 */  4 #include <cstdio>  5 #include <iostream>  6 #include <algorithm>  7 #include <cstring>  8 using namespace std;  9 10 typedef long long ll; 11 12 const int MAXN = 1e6 + 10; 13 const int INF = 0x3f3f3f3f; 14 const int MOD = 1e9 + 7; 15 ll dp[MAXN]; 16 17 void solve(void) 18 { 19 dp[1] = 1; dp[2] = 2; 20 for (int i=3; i<=1e6; ++i) 21  { 22 dp[i] = (dp[i-1] + (i - 1) * dp[i-2]) % MOD; 23  } 24 } 25 26 int main(void) //2015百度之星资格赛 1001 大搬家 27 { 28  solve (); 29 int t, cas = 0; 30 scanf ("%d", &t); 31 while (t--) 32  { 33 int n; scanf ("%d", &n); 34 printf ("Case #%d:\n", ++cas); 35 printf ("%I64d\n", dp[n]); 36  } 37 38 return 0; 39 } 40 41 42 /* 43 2 44 1 45 3 46 */