Decode Ways II

Problem

Count the ways to decode a string of digits and star wildcards, where a star matches any digit 1 to 9 and letters map from 1 to 26.

Use dynamic programming with helper counts: a wildcard single digit gives 9 choices, and a leading wildcard contributes 15 valid two-digit groups. Return 0 for the empty string.

Hint

Count single-digit and two-digit transitions separately, using the previous two dp values.

Test cases

case 1

in: ["*"]

expected: 9

case 2

in: ["1*"]

expected: 18

case 3

in: ["2*"]

expected: 15

case 4

in: ["**"]

expected: 96

case 5

in: ["0"]

expected: 0

case 6

in: ["11106"]

expected: 2

Starter codePython

def num_decodings_ii(s):
    # Your code here
    pass

6 test cases · run your code against them in the editor