830. Positions of Large Groups LeetCode Solution

In this guide, you will get 830. Positions of Large Groups LeetCode Solution with the best time and space complexity. The solution to Positions of Large Groups problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Table of Contents

1. Problem Statement
2. Complexity Analysis
3. Positions of Large Groups solution in C++
4. Positions of Large Groups solution in Java
5. Positions of Large Groups solution in Python
6. Additional Resources

Problem Statement of Positions of Large Groups

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.

Complexity Analysis

• Time Complexity: O(n)
• Space Complexity: O(n)

830. Positions of Large Groups LeetCode Solution in C++

class Solution {
 public:
  vector<vector<int>> largeGroupPositions(string s) {
    const int n = s.length();
    vector<vector<int>> ans;

    for (int i = 0, j = 0; i < n; i = j) {
      while (j < n && s[j] == s[i])
        ++j;
      if (j - i >= 3)
        ans.push_back({i, j - 1});
    }

    return ans;
  }
};
/* code provided by PROGIEZ */

830. Positions of Large Groups LeetCode Solution in Java

class Solution {
  public List<List<Integer>> largeGroupPositions(String s) {
    final int n = s.length();
    List<List<Integer>> ans = new ArrayList<>();

    for (int i = 0, j = 0; i < n; i = j) {
      while (j < n && s.charAt(j) == s.charAt(i))
        ++j;
      if (j - i >= 3)
        ans.add(Arrays.asList(i, j - 1));
    }

    return ans;
  }
}
// code provided by PROGIEZ

830. Positions of Large Groups LeetCode Solution in Python

class Solution:
  def largeGroupPositions(self, s: str) -> list[list[int]]:
    n = len(s)
    ans = []
    i = 0
    j = 0

    while i < n:
      while j < n and s[j] == s[i]:
        j += 1
      if j - i >= 3:
        ans.append([i, j - 1])
      i = j

    return ans
 # code by PROGIEZ

Additional Resources

• Explore all LeetCode problem solutions at Progiez here
• Explore all problems on LeetCode website here

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