From 867236519563387f44ad282089eb8f65761f4d07 Mon Sep 17 00:00:00 2001
From: tom4649 <tkaaynakiyoshi@gmail.com>
Date: Sat, 22 Aug 2026 09:01:19 +0900
Subject: [PATCH] step1,2

---
 0777.Swap-Adjacent-in-LR-String/memo.md  | 20 +++++++++++++++
 0777.Swap-Adjacent-in-LR-String/step1.py | 31 ++++++++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 0777.Swap-Adjacent-in-LR-String/memo.md
 create mode 100644 0777.Swap-Adjacent-in-LR-String/step1.py

diff --git a/0777.Swap-Adjacent-in-LR-String/memo.md b/0777.Swap-Adjacent-in-LR-String/memo.md
new file mode 100644
index 0000000..70ce178
--- /dev/null
+++ b/0777.Swap-Adjacent-in-LR-String/memo.md
@@ -0,0 +1,20 @@
+# 777. Swap Adjacent in LR String
+
+## step1
+最初 *.replace("X", "")を比較することを考えたが、L, Rの移動が一方に制限されているため誤り。
+
+pointerでscanすることで解決。
+
+## step2
+
+https://leetcode.com/problems/swap-adjacent-in-lr-string/solutions/6970523/python-simple-two-pointers-by-rnotappl-yeij/?envType=problem-list-v2&envId=7p55wqm
+
+同じ解法。ただし、こちらはwhileの条件が and でループの前にXの個数の一致を確認している。
+
+これ以外の解法はない？
+
+https://leetcode.com/problems/swap-adjacent-in-lr-string/solutions/2047353/python-on-with-comments-and-reasonings-b-kkw3/?envType=problem-list-v2&envId=7p55wqm
+インデックスを全て保存する
+
+## step3
+TODO
diff --git a/0777.Swap-Adjacent-in-LR-String/step1.py b/0777.Swap-Adjacent-in-LR-String/step1.py
new file mode 100644
index 0000000..071c102
--- /dev/null
+++ b/0777.Swap-Adjacent-in-LR-String/step1.py
@@ -0,0 +1,31 @@
+class Solution:
+    def canTransform(self, start: str, result: str) -> bool:
+        if len(start) != len(result):
+            return False
+        if not start:
+            return True
+
+        index_start = 0
+        index_result = 0
+
+        while index_start < len(start) or index_result < len(result):
+            while index_start < len(start) and start[index_start] == "X":
+                index_start += 1
+            while index_result < len(result) and result[index_result] == "X":
+                index_result += 1
+
+            if index_start == len(start) or index_result == len(result):
+                return index_start == index_result
+
+            if start[index_start] != result[index_result]:
+                return False
+
+            if start[index_start] == "L" and index_start < index_result:
+                return False
+            if start[index_start] == "R" and index_result < index_start:
+                return False
+
+            index_start += 1
+            index_result += 1
+
+        return True