reverse bits solution

Author: hyer0705

reverse-bits/hyer0705.ts

@@ -0,0 +1,45 @@
+// 8비트로 쪼갠 방법
+function reverseBits(n: number): number {
+  const TOTAL_BITS = 32;
+  const BITS_IN_BYTE = 8;
+  const BYTES_IN_INTEGER = TOTAL_BITS / BITS_IN_BYTE;
+  const BYTE_MASK = 0xff;
+
+  let result = 0;
+
+  const reversedByteCache: number[] = Array.from({ length: 2 ** BITS_IN_BYTE }, (_, n) => {
+    let reversedNum = 0;
+
+    for (let i = 0; i < BITS_IN_BYTE; i++) {
+      const bit = (n >>> i) & 1;
+      reversedNum |= bit << (BITS_IN_BYTE - 1 - i);
+    }
+
+    return reversedNum;
+  });
+
+  for (let i = 0; i < BYTES_IN_INTEGER; i++) {
+    const byte = (n >>> (i * BITS_IN_BYTE)) & BYTE_MASK;
+
+    const reversed = reversedByteCache[byte];
+    result |= reversed << (TOTAL_BITS - (i + 1) * BITS_IN_BYTE);
+  }
+
+  return result >>> 0;
+}
+
+// 32번 연산 방법
+function reverseBits(n: number): number {
+  const BITS_LEN = 32;
+
+  let reversed = 0;
+
+  for (let i = 0; i < BITS_LEN; i++) {
+    const bit = (n >>> i) & 1;
+
+    const reversedPosition = 31 - i;
+    reversed |= bit << reversedPosition;
+  }
+
+  return reversed >>> 0;
+}