# Time: O(2n)  where n is the length of the array, cause every letter was checked once
# Space: O(1)
'''
         i
start = "RXXLRXRXL"
end =   "XXLXXRRLX"
           j
L - R:  x
R - L:  x
L - L： i >= j  -> i < j: x
R - R： i <= j  -> i > j: x


"XXRXLXRXXX"
"XXRLXXXXXR"
'''

class Solution(object):
    def canTransform(self, start, end):
        """
        :type start: str
        :type end: str
        :rtype: bool
        """
        i = j = 0
        if start.replace("X","") != end.replace('X',""):
            return False

        n = len(start)
        for i in range(len(start)):
            if start[i] != 'X':
                while j < n and end[j] == 'X':
                    j += 1
                if start[i] == 'L':
                    if i < j:
                        return False
                else:
                    if i > j:
                        return False
                j += 1
        return True