DSA · Bit Manipulation · #47

Bitwise AND of Numbers Range

Module 50 · difficulty 3/5·⏱ 30:00starts on first keystroke

Given two integers `left` and `right` that represent the inclusive range `[left, right]`, return the bitwise AND of all numbers in this range. Implement the function `rangeBitwiseAnd(left, right)`. Key insight: a bit position is `1` in the result only if it is `1` for *every* number in the range. The result is exactly the **common binary prefix** of `left` and `right`, with all lower bits set to `0`.

Examples

left = 5, right = 7 → 4 — 5=101, 6=110, 7=111. AND = 100 = 4.
left = 0, right = 0 → 0
left = 1, right = 2147483647 → 0 — The range spans bit boundaries, so no high bit survives.

Constraints

· 0 <= left <= right <= 2^31 - 1

Session phases

A · Clarify

B · Approach

C · Complexity

D · Edges

E · Code

F · Tradeoff

G · Score

Phase A — Clarify

Ask questions about input bounds, types, and edge constraints.

Ask the coach clarifying questions about the problem.

When you've covered this phase, advance to the next.