public class Solution
extends Object
1419 - Minimum Number of Frogs Croaking\.
Medium
You are given the string `croakOfFrogs`, which represents a combination of the string `"croak"` from different frogs, that is, multiple frogs can croak at the same time, so multiple `"croak"` are mixed.
_Return the minimum number of_ different _frogs to finish all the croaks in the given string._
A valid `"croak"` means a frog is printing five letters `'c'`, `'r'`, `'o'`, `'a'`, and `'k'` **sequentially**. The frogs have to print all five letters to finish a croak. If the given string is not a combination of a valid `"croak"` return `-1`.
**Example 1:**
**Input:** croakOfFrogs = "croakcroak"
**Output:** 1
**Explanation:** One frog yelling "croak**"** twice.
**Example 2:**
**Input:** croakOfFrogs = "crcoakroak"
**Output:** 2
**Explanation:** The minimum number of frogs is two. The first frog could yell "**cr**c**oak**roak". The second frog could yell later "cr**c**oak**roak**".
**Example 3:**
**Input:** croakOfFrogs = "croakcrook"
**Output:** -1
**Explanation:** The given string is an invalid combination of "croak**"** from different frogs.
**Constraints:**
* 1 <= croakOfFrogs.length <= 105
* `croakOfFrogs` is either `'c'`, `'r'`, `'o'`, `'a'`, or `'k'`.