problem_3.py

def getLargestString(word, k):
    countArr = [0]*26
    a, ans = ord('a'), []
    for c in word:
        countArr[ord(c)-a] += 1
    i = 25
    while i >= 0:
        if countArr[i] > k:
            letter = chr(i+a)
            ans.append(letter*k)
            countArr[i] -= k
            j = i-1
            while(countArr[j] <= 0 and j>0):
                j -= 1
            if countArr[j] > 0 and j >= 0:
                letter = chr(j+a)
                ans.append(letter)
                countArr[j] -= 1
            else:
                break
        elif countArr[i] > 0:
            letter = chr(i+a)
            ans.append(letter*countArr[i])
            countArr[i] = 0 
        else:
            i -= 1

    return ''.join(ans)