leetcode

0 class Solution {

1 static const int MOD = 1E9 + 7;

2

3 public:

4 int countVowelPermutation(int n) {

5 long dp[5], pdp[5] = {1, 1, 1, 1, 1};

6 for (int i = 1; i < n; i++) {

7 dp[0] = (pdp[1] + pdp[2] + pdp[4]) % MOD;

8 dp[1] = (pdp[0] + pdp[2]) % MOD;

9 dp[2] = (pdp[1] + pdp[3]) % MOD;

10 dp[3] = (pdp[2]) % MOD;

11 dp[4] = (pdp[2] + pdp[3]) % MOD;

12 swap(dp, pdp);

13 }

14 int res = 0;

15 for (int i = 0; i < 5; i++)

16 res = (res + pdp[i]) % MOD;

17 return res;

18 }

19 };