Today I have done leetcode's May LeetCoding Challenge with cpp.

May LeetCoding Challenge 11

Description

Count Sorted Vowel Strings

Given an integer n, return the number of strings of length n that consist only of vowels (a, e, i, o, u) and are lexicographically sorted.

A string s is lexicographically sorted if for all valid i, s[i] is the same as or comes before s[i+1] in the alphabet.

Example 1:

Input: n = 1
Output: 5
Explanation: The 5 sorted strings that consist of vowels only are ["a","e","i","o","u"].

Example 2:

Input: n = 2
Output: 15
Explanation: The 15 sorted strings that consist of vowels only are
["aa","ae","ai","ao","au","ee","ei","eo","eu","ii","io","iu","oo","ou","uu"].
Note that "ea" is not a valid string since 'e' comes after 'a' in the alphabet.

Example 3:

Input: n = 33
Output: 66045

Constraints:

• 1 <= n <= 50

Solution

class Solution {
public:
  int countVowelStrings(int n) {
    int dp[5] = {1, 1, 1, 1, 1};
    for(int i = 1; i < n; ++i) {
      for(int j = 1; j < 5; ++j) dp[j] += dp[j-1];
    }
    int answer = 0;
    for(int i = 0; i < 5; ++i) answer += dp[i];
    return answer;
  }
};

// Accepted
// 41/41 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 85.48 % of cpp submissions (5.8 MB)