Create 844. Backspace String Compare.md

844. Backspace String Compare.md

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+# 844. Backspace String Compare
+https://leetcode.com/problems/backspace-string-compare/
+
+# 1st
+#があると一つ前の文字を消去、最終的に残ったものを比較ということで、   
+最後に入れたものを削除しやすいスタックを選択
+
+```python
+class Solution:
+    def backspaceCompare(self, s: str, t: str) -> bool:
+        s_stack = []
+        t_stack = []
+
+        for s_1 in s:
+            if s_1 != '#':
+                s_stack.append(s_1)
+            elif len(s_stack) != 0:
+                s_stack.pop()
+        for t_1 in t:
+            if t_1 != '#':
+                t_stack.append(t_1)
+            elif len(t_stack) != 0:
+                t_stack.pop()
+
+
+        if len(s_stack) != len(t_stack):
+            return False
+
+        loop_cnt = len(s_stack)
+        while loop_cnt > 0:
+            if s_stack.pop() != t_stack.pop():
+                return False
+            loop_cnt -= 1
+
+        return True
+```    
+
+# 2nd・3rd
+s1・t1をcharに変更しました
+```python
+class Solution:
+    def backspaceCompare(self, s: str, t: str) -> bool:
+        s_stack = []
+        t_stack = []
+
+        for char in s:
+            if char != '#':
+                s_stack.append(char)
+            elif len(s_stack) != 0:
+                s_stack.pop()
+        for char in t:
+            if char != '#':
+                t_stack.append(char)
+            elif len(t_stack) != 0:
+                t_stack.pop()
+
+
+        if len(s_stack) != len(t_stack):
+            return False
+
+        loop_cnt = len(s_stack)
+        while loop_cnt > 0:
+            if s_stack.pop() != t_stack.pop():
+                return False
+            loop_cnt -= 1
+
+        return True
+
+
+```
+
+# 4th レビューを基に再構築
+```python
+class Solution:
+    def backspaceCompare(self, s: str, t: str) -> bool:
+        def backspace_string(x):
+            x_stack = []
+            for c in x:
+                if c == '#':
+                    if x_stack:
+                        x_stack.pop()
+                    continue
+                x_stack.append(c)
+            return x_stack
+
+        return backspace_string(s) == backspace_string(t)
+```