1641. Count Sorted Vowel Strings

Solution.ts

// https://leetcode.com/problems/count-sorted-vowel-strings/
function countVowelStrings(n: number): number {
    return traverse(n, 0, 0);;
};

const vowels: string[] = [ 'a', 'e', 'i', 'o', 'u' ];
function traverse(n: number, runningCombination: number, runningIdx: number): number {
    if(runningCombination == n) {
        return 1;
    }
       
    let combinationSum = 0;
    for(let idx: number = runningIdx; idx < vowels.length; idx++) {
        runningCombination++;
        combinationSum += traverse(n, runningCombination, idx);
        runningCombination--;
    }
    
    return combinationSum;
}