Deviopath › JavaScript

Decode Ways

Hard · Dynamic Programming

Letters are encoded as numbers: "A" is "1", "B" is "2", ... "Z" is "26". Write a function numDecodings that returns how many ways a non-empty digit string s can be decoded back into letters.

A code cannot start with 0: "06" is not a valid code for "F", and a lone "0" is invalid. If the string cannot be decoded at all, return 0.

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