# Positions Of Large Groups Problem

## Description

LeetCode Problem 830.

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], wherestartandenddenote the start and endindices (inclusive) of the group. In the above example,”xxxx”has the interval[3,6].

A group is consideredlargeif it has 3 or more characters.

Returnthe intervals of every large group sorted inincreasing order by start index.

Example 1:

``````1
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Input: s = "abbxxxxzzy"
Output: [[3,6]]
Explanation: "xxxx" is the only large group with start index 3 and end index 6.
``````

Example 2:

``````1
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Input: s = "abc"
Output: []
Explanation: We have groups "a", "b", and "c", none of which are large groups.
``````

Example 3:

``````1
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Input: s = "abcdddeeeeaabbbcd"
Output: [[3,5],[6,9],[12,14]]
Explanation: The large groups are "ddd", "eeee", and "bbb".
``````

Example 4:

``````1
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Input: s = "aba"
Output: []
``````

Constraints:

• 1 <= s.length <= 1000
• s contains lower-case English letters only.

## Sample C++ Code

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class Solution {
public:
vector<vector<int>> largeGroupPositions(string s) {
vector<vector<int>> res;
int left = 0, right = 0;
while (left < s.size()) {
while (s[left] == s[right])
right++;
if (right - left >= 3)
res.push_back({left, right-1});
left = right;
}
return res;
}
};
``````