Reverse bits of a given 32-bits unsigned integer.

Example 1:

• Input: n = 43261596
• Output: 964176192

Constraints:

• Input must be a 32-bit unsigned integer

Extract last bit of n, shift result left, shift n right, 32 times.

Bit Shifting Loop

graph TD
    A["Input Integer / Bits"] --> B["Apply Bitwise Operation (AND / XOR / Shift)"]
    B --> C{"Check Bit Condition"}
    C -- "Condition Met" --> D["Update Bit Count / Result"]
    C -- "Continue" --> E["Shift Bits (>>> 1 or & n-1)"]
    E --> B
    D --> F["Return Final Result"]

function reverseBits(n) {
  let res = 0;
  for (let i = 0; i < 32; i++) {
    res = (res << 1) | (n & 1);
    n >>>= 1;
  }
  return res >>> 0;
}

• Time Complexity: O(32)
• Space Complexity: O(1)
• Explanation: 32 bit shifts.

function reverseBits(n) {
  let res = 0;
  for (let i = 0; i < 32; i++) {
    res = (res << 1) | (n & 1);
    n >>>= 1;
  }
  return res >>> 0;
}

• Time Complexity: O(32)
• Space Complexity: O(1)
• Explanation: Bitwise reverse using bit shift.

1. Initialize State: Setup necessary pointers, dynamic programming arrays, or hash maps.
2. Iterate & Evaluate: Process the input according to the boundary conditions.
3. Update & Return: Compute the optimal answer and return early or at termination.

Iterate 32 times, extracting lowest bit of n and adding it to res.

1. Process all 32 bits from right to left.

👉 Solve this problem interactively in the DSA Lab