#include "leetcode.h" class Solution { public: int countVowelStrings(int n) { int a = 1, e = 1, i = 1, o = 1, u = 1; while (--n) { o += u; i += o; e += i; a += e; } return a + e + i + o + u; } }; int main() { Solution obj; cout << obj.countVowelStrings(1); }