README.md

1849. Splitting a String Into Descending Consecutive Values

You are given a string s that consists of only digits.

Check if we can split s into two or more non-empty substrings such that the numerical values of the substrings are in descending order and the difference between numerical values of every two adjacent substrings is equal to 1.

• For example, the string s = "0090089" can be split into ["0090", "089"] with numerical values [90,89]. The values are in descending order and adjacent values differ by 1, so this way is valid.
• Another example, the string s = "001" can be split into ["0", "01"], ["00", "1"], or ["0", "0", "1"]. However all the ways are invalid because they have numerical values [0,1], [0,1], and [0,0,1] respectively, all of which are not in descending order.

Return true if it is possible to split s as described above, or false otherwise.

A substring is a contiguous sequence of characters in a string.

Example 1:

Input: s = "1234"
Output: false
Explanation: There is no valid way to split s.

Example 2:

Input: s = "050043"
Output: true
Explanation: s can be split into ["05", "004", "3"] with numerical values [5,4,3].
The values are in descending order with adjacent values differing by 1.

Example 3:

Input: s = "9080701"
Output: false
Explanation: There is no valid way to split s.

Constraints:

• 1 <= s.length <= 20
• s only consists of digits.

Solutions (Python)

1. Solution

from functools import cache


class Solution:
    @cache
    def splitString(self, s: str, x: int = None) -> bool:
        if x is None:
            return any(self.splitString(s[i:], int(s[:i])) for i in range(1, len(s)))

        if s == "":
            return True

        return any(x - 1 == int(s[:i]) and self.splitString(s[i:], int(s[:i])) for i in range(1, len(s) + 1))