diff --git a/0190.Reverse-Bits/memo.md b/0190.Reverse-Bits/memo.md
new file mode 100644
index 0000000..69602a0
--- /dev/null
+++ b/0190.Reverse-Bits/memo.md
@@ -0,0 +1,52 @@
+# 190. Reverse Bits
+
+## step1
+strに直してreverseする。f-stringのフォーマットが分からず、調べた。
+
+https://docs.python.org/ja/3/tutorial/inputoutput.html#formatted-string-literals
+https://docs.python.org/ja/3/library/string.html#formatspec
+
+bが2進数、x (Xで大文字)で16進数、#を付けるとプレフィックスが付く
+
+0(桁数)で0埋め。他を書くときには><^などを書く
+
+```python
+>>> num = 42
+>>> print(f"{num:b}")
+101010
+>>> print(f"{num:x}")
+2a
+>>> print(f"{num:#x}")
+0x2a
+>>> print(f"{num:#X}")
+0X2A
+>>> print(f"{num:03b}")
+101010
+>>> print(f"{num:03x}")
+02a
+>>> print(f"{num:-3x}")
+ 2a
+>>> print(f"{num:,3x}")
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+ValueError: Invalid format specifier ',3x' for object of type 'int'
+>>> print(f"{num:,>3x}")
+,2a
+>>> print(f"{num:,^6x}")
+,,2a,,
+```
+
+bit演算でも書く。
+
+## step2
+https://github.com/Kitaken0107/GrindEasy/pull/23
+
+> 文字列に変換しないでやってみてください。ビット操作の問題だと思います。
+
+> 32 bit 整数って、シフト演算をして、最下位ビットを見ると、スタックみたいなものじゃないですか。
+
+---
+以下を追加
+- builtin (c++)
+- divide and conquer
+- 配列を前計算しておく
diff --git a/0190.Reverse-Bits/step1.py b/0190.Reverse-Bits/step1.py
new file mode 100644
index 0000000..98df0c1
--- /dev/null
+++ b/0190.Reverse-Bits/step1.py
@@ -0,0 +1,5 @@
+class Solution:
+    def reverseBits(self, n: int) -> int:
+        bit_expression = f"{n:032b}"
+        return int(bit_expression[::-1], 2)
+
diff --git a/0190.Reverse-Bits/step1_bit.py b/0190.Reverse-Bits/step1_bit.py
new file mode 100644
index 0000000..f87d6cd
--- /dev/null
+++ b/0190.Reverse-Bits/step1_bit.py
@@ -0,0 +1,12 @@
+class Solution:
+    def reverseBits(self, n: int) -> int:
+        reversed_bits = 0
+        num_bits = 0
+        while num_bits < 32:
+            reversed_bits <<= 1
+            reversed_bits |= n & 1
+            n >>= 1
+            num_bits += 1
+        return reversed_bits
+
+
diff --git a/0190.Reverse-Bits/step2_builtin.cpp b/0190.Reverse-Bits/step2_builtin.cpp
new file mode 100644
index 0000000..a0adb35
--- /dev/null
+++ b/0190.Reverse-Bits/step2_builtin.cpp
@@ -0,0 +1,8 @@
+#include <cstdint>
+
+class Solution {
+public:
+    uint32_t reverseBits(uint32_t n) {
+        return __builtin_bitreverse32(n);
+    }
+};
diff --git a/0190.Reverse-Bits/step2_divide_and_conquer.py b/0190.Reverse-Bits/step2_divide_and_conquer.py
new file mode 100644
index 0000000..8f69a76
--- /dev/null
+++ b/0190.Reverse-Bits/step2_divide_and_conquer.py
@@ -0,0 +1,10 @@
+class Solution:
+    def reverseBits(self, n: int) -> int:
+        n = n & 0xffffffff
+        n = ((n & 0x55555555) << 1) | ((n & 0xaaaaaaaa) >> 1)
+        n = ((n & 0x33333333) << 2) | ((n & 0xcccccccc) >> 2)
+        n = ((n & 0x0f0f0f0f) << 4) | ((n & 0xf0f0f0f0) >> 4)
+        n = ((n & 0x00ff00ff) << 8) | ((n & 0xff00ff00) >> 8)
+        n = ((n & 0x0000ffff) << 16) | ((n & 0xffff0000) >> 16)
+
+        return n & 0xffffffff
diff --git a/0190.Reverse-Bits/step2_memory.py b/0190.Reverse-Bits/step2_memory.py
new file mode 100644
index 0000000..ee58750
--- /dev/null
+++ b/0190.Reverse-Bits/step2_memory.py
@@ -0,0 +1,21 @@
+class Solution:
+    REVERSE_TABLE = [0] * 256
+
+    @classmethod
+    def init_table(cls):
+        for i in range(1, 256):
+            cls.REVERSE_TABLE[i] = (cls.REVERSE_TABLE[i >> 1] >> 1) | ((i & 1) << 7)
+
+    def __init__(self):
+        if self.REVERSE_TABLE[1] == 0:
+            self.init_table()
+
+    def reverseBits(self, n: int) -> int:
+        n = n & 0xffffffff
+
+        byte0 = self.REVERSE_TABLE[n & 0xff]
+        byte1 = self.REVERSE_TABLE[(n >> 8) & 0xff]
+        byte2 = self.REVERSE_TABLE[(n >> 16) & 0xff]
+        byte3 = self.REVERSE_TABLE[(n >> 24) & 0xff]
+
+        return (byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3
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