1220-Count-Vowels-Permutation.py

class Solution:    
    Memo = {}    
    def countVowelPermutation(self, n, c = '') -> int:        
        if (c, n) in self.Memo:            
            return self.Memo[(c, n)]
        if n == 1:
            if c == 'a':
                return 1 
            if c == 'e':
                return 2 
            if c == 'i':
                return 4 
            if c == 'o':
                return 2 
            if c == 'u':
                return 1            
            if c == '':                
                return 5
        else:
            if c == 'a':
                self.Memo[('a', n)] = self.countVowelPermutation(n - 1, 'e')                
                return self.Memo[('a', n)]
            if c == 'e':
                self.Memo[('e', n)] = self.countVowelPermutation(n - 1, 'a') + self.countVowelPermutation(n - 1, 'i')                
                return self.Memo[('e', n)]
            if c == 'i':
                self.Memo[('i', n)] = self.countVowelPermutation(n - 1, 'a') + self.countVowelPermutation(n - 1, 'e') + self.countVowelPermutation(n - 1, 'o') + self.countVowelPermutation(n - 1, 'u')          
                return self.Memo[('i', n)]
            if c == 'o':
                self.Memo[('o', n)] = self.countVowelPermutation(n - 1, 'i') + self.countVowelPermutation(n - 1, 'u')                
                return self.Memo[('o', n)]
            if c == 'u':
                self.Memo[('u', n)] = self.countVowelPermutation(n - 1, 'a')                
                return self.Memo[('u', n)]
            if c == '':
                Tot = 0
                for i in ['a', 'e', 'i', 'o', 'u']:
                    Tot = Tot + self.countVowelPermutation(n - 1, i);                    
                return Tot % 1000000007