--- id: binary title: Binary --- ## Study links - [Bits, Bytes, Building With Binary](https://medium.com/basecs/bits-bytes-building-with-binary-13cb4289aafa) ## Notes Questions involving binary representations and bitwise operations are asked sometimes and you must be absolutely familiar with how to convert a number from decimal form into binary form (and vice versa) in your chosen programming language. Some helpful utility snippets: - Test k^th bit is set: `num & (1 << k) != 0`. - Set k^th bit: `num |= (1 << k)`. - Turn off k^th bit: `num &= ~(1 << k)`. - Toggle the k^th bit: `num ^= (1 << k)`. - To check if a number is a power of 2, `(num & num - 1) == 0` or `(num & (-num)) == num`. - Swapping two variables: `num1 ^= num2; num2 ^= num1; num1 ^= num2` ## Corner cases - Be aware and check for overflow/underflow - Negative numbers ## Recommended LeetCode questions - [Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/) - [Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits/) - [Counting Bits](https://leetcode.com/problems/counting-bits/) - [Missing Number](https://leetcode.com/problems/missing-number/) - [Reverse Bits](https://leetcode.com/problems/reverse-bits/)