PYTHON

smallest string with a given numeric value

def solve(n, k):
   string = ""
   while n > 0:
      letter = min(26, k-n+1)
      string += chr(letter + ord('a') - 1)
      k -= letter
      n -= 1
   return string[::-1]

n = 4
k = 16
print(solve(n, k))