A discount coupon ([a-z]) is valid if it follows one of the 3 conditions:
- An empty string is a valid coupon
- A valid coupon with
xon either side of it is also valid (xAxis a valid coupon) - A concatentation of 2 valid coupons
AandBis a also valid coupon (AB&BAare both valid)
Input: []string of discount codes
Output: []int32 with 1 at ith position if the discount code ith i valid otherwise 0
Example:
Input := []string{"abba", "abc", "daaccd"}
Output := []int32{1, 0, 1}
// `abba`: With Rule 1 empty string is valid.
// Adding `b` to both size keeps it valid by rule 2,
// Similarly adding `a` on both sides keeps it valid
// `abc`: It's not valid by any rule
// `daaccd`: `aa` is valid by rule 1 and so is `cc`.
// Concatenation of them is valid by rule 3 and
// adding `d` to either side keeps it valid by rule 1Comments (2)