830 - Positions of Large Groups\.

Easy

In a string s of lowercase letters, these letters form consecutive groups of the same character.

For example, a string like s = "abbxxxxzyy" has the groups "a", "bb", "xxxx", "z", and "yy".

A group is identified by an interval [start, end], where start and end denote the start and end indices (inclusive) of the group. In the above example, "xxxx" has the interval [3,6].

A group is considered large if it has 3 or more characters.

Return the intervals of every large group sorted in increasing order by start index.

Example 1:

Input: s = "abbxxxxzzy"

Output: [3,6]

Explanation: "xxxx" is the only large group with start index 3 and end index 6.

Example 2:

Input: s = "abc"

Output: []

Explanation: We have groups "a", "b", and "c", none of which are large groups.

Example 3:

Input: s = "abcdddeeeeaabbbcd"

Output: [3,5,6,9,12,14]

Explanation: The large groups are "ddd", "eeee", and "bbb".

Constraints:

• 1 <= s.length <= 1000

• s contains lowercase English letters only.