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". Example 4:
Input: s = "aba" Output: []
Constraints:
1 <= s.length <= 1000 s contains lower-case English letters only.
public class Solution {
public IList<IList<int>> LargeGroupPositions(string s) {
var result = new List<IList<int>>();
if(s.Length==0){
return result;
}
char last = s[0];
int count = 1;
int start = 0;
for(int i=1;i<s.Length;i++){
if(s[i]==last){
count++;
}
else{
if(count>=3){
var data = new List<int>();
data.Add(start);
data.Add(i-1);
result.Add(data);
}
last = s[i];
count = 1;
start = i;
}
}
if(count>=3)
{
var data = new List<int>();
data.Add(start);
data.Add(s.Length-1);
result.Add(data);
}
return result;
}
}Time Complexity: O(n)
Space Complexity: O(1)
