Solution of 830

800-900q/830.py

@@ -0,0 +1,54 @@
+'''
+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]]
+        """
+        if not S:
+            return []
+
+        result = []
+        count = 1
+        prevChar = S[0]
+        index_i = 0
+        for index in range(1,len(S)):
+            if S[index] == prevChar:
+                count += 1
+            else:
+                if count >= 3:
+                    result.append([index_i, index-1])
+
+                count = 1
+                prevChar = S[index]
+                index_i = index
+
+        if count >= 3:
+            result.append([index_i, len(S)-1])
+        return result