10198 - Counting/10198.cpp

   1 using namespace std;
   2 #include <algorithm>
   3 #include <iostream>
   4 #include <iterator>
   5 #include <sstream>
   6 #include <fstream>
   7 #include <cassert>
   8 #include <climits>
   9 #include <cstdlib>
  10 #include <cstring>
  11 #include <string>
  12 #include <cstdio>
  13 #include <vector>
  14 #include <cmath>
  15 #include <queue>
  16 #include <deque>
  17 #include <stack>
  18 #include <list>
  19 #include <map>
  20 #include <set>
  21
  22 #define D(x) cout << #x " is " << x << endl
  23
  24 long long dp[1010];
  25
  26 int main(){
  27   dp[0] = 1;
  28   for (int i=0; i<=1000; ++i){
  29     dp[i+1] += 2*dp[i];
  30     dp[i+2] += dp[i];
  31     dp[i+3] += dp[i];
  32   }
  33   int n;
  34   while (cin >> n) cout << dp[n] << endl;
  35   return 0;
  36 }