positions-of-large-groups.py

# 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".

# Call a group large if it has 3 or more characters.  We would like the starting and ending positions of every large group.

# The final answer should be in lexicographic order.

 

# Example 1:

# Input: "abbxxxxzzy"
# Output: [[3,6]]
# Explanation: "xxxx" is the single large group with starting  3 and ending positions 6.
# Example 2:

# Input: "abc"
# Output: []
# Explanation: We have "a","b" and "c" but no large group.
# Example 3:

# Input: "abcdddeeeeaabbbcd"
# Output: [[3,5],[6,9],[12,14]]

class Solution(object):
    def largeGroupPositions(self, S):
        """
        :type S: str
        :rtype: List[List[int]]
        """
        result=[]
        i=0
        j=1

        while j < len(S):            
            while(j<len(S) and S[i]==S[j]):                     
                j=j+1
            if(j-i>=3):
                result.append([i,j-1])
            i=j
            j=j+1            
        return result

s=Solution()
print(s.largeGroupPositions("a"))