777. Swap Adjacent in LR String

In a string composed of 'L', 'R', and 'X' characters, like "RXXLRXRXL", a move consists of either replacing one occurrence of "XL" with "LX", or replacing one occurrence of "RX" with "XR". Given the starting string start and the ending string end, return True if and only if there exists a sequence of moves to transform one string to the other.

Example 1:

Input: start = "RXXLRXRXL", end = "XRLXXRRLX"
Output: true
Explanation: We can transform start to end following these steps:
RXXLRXRXL ->
XRXLRXRXL ->
XRLXRXRXL ->
XRLXXRRXL ->
XRLXXRRLX

Example 2:

Input: start = "X", end = "L"
Output: false

Example 3:

Input: start = "LLR", end = "RRL"
Output: false

Example 4:

Input: start = "XL", end = "LX"
Output: true

Example 5:

Input: start = "XLLR", end = "LXLX"
Output: false

Constraints:

• 1 <= start.length <= 104
• start.length == end.length
• Both start and end will only consist of characters in 'L', 'R', and 'X'.

# @lc code=start
using LeetCode

function can_transform(s::String, t::String)
    i, j = 1, 1
    len = length(s)
    len != length(t) && return false
    while i <= len || j <= len
        while i <= len && s[i] == 'X'; i += 1; end
        while j <= len && t[j] == 'X' ; j += 1; end
        ((i <= len) ⊻ (j <= len)) && return false
        if i <= len && j <= len
            (s[i] != t[j] || (s[i] == 'L' && i < j) || (s[i] == 'R' && i > j)) && return false
        end
        i += 1; j += 1
    end
    return true
end
# @lc code=end

can_transform (generic function with 1 method)

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