Medium
You are given a string s consisting of lowercase English letters.
In one operation, you can select any of s that is not the entire string and sort it in non-descending alphabetical order.
Return the minimum number of operations required to make s sorted in non-descending order. If it is not possible, return -1.
Example 1:
Input: s = "dog"
Output: 1
Explanation:
- Sort substring
"og"to"go". - Now,
s = "dgo", which is sorted in ascending order. Thus, the answer is 1.
Example 2:
Input: s = "card"
Output: 2
Explanation:
- Sort substring
"car"to"acr", sos = "acrd". - Sort substring
"rd"to"dr", makings = "acdr", which is sorted in ascending order. Thus, the answer is 2.
Example 3:
Input: s = "gf"
Output: -1
Explanation:
- It is impossible to sort
sunder the given constraints. Thus, the answer is -1.
Constraints:
1 <= s.length <= 105sconsists of only lowercase English letters.