# Tag: Bit Hacks

## Swap individual bits at given position in an integer

Given an integer, swap consecutive b bits starting from given positions in binary representation of the integer. The bits to be swapped should not overlap with each other.

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## Multiply 16-bit integers using 8-bit multiplier

Given two 16-bit positive values stored in 32-bit integer variables, find the product using the 8-bit multiply operator that that takes two 8-bit numbers and returns a 16-bit value.

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## Compute parity of a number using lookup table

Given an integer, calculate its Parity. The parity refers to the number of 1’s in a given binary number.   Odd parity (encoded as 1) means there are an odd number of 1’s and even parity (encoded as 0) means that there are an even number of 1’s. Parity bits are often used as a …

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## Bit Hacks – Part 6 (Random Problems)

In this post, we will discuss few unrelated problems that can be solved using bit manipulation hacks.   Below Problems are covered in this post – Problem 1. Find number of bits needed to be flipped to convert given integer to another Problem 2. Conditionally negate a value without branching Problem 3. Find XOR of …

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## Bit Hacks – Part 5 (Find absolute value of an integer without branching)

Given an integer, compute its absolute value (abs) without branching     We can use the expression ((n + mask) ^ mask) where mask is (n >> 31) (assuming 32 bit storage for integers) to compute the absolute value of n. The mask (n >> 31) will be evaluated to 0 for positive numbers and …

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## Bit Hacks – Part 4 (Playing with letters of English alphabet)

In this post we will discuss some of the bit hacks/tricks on letters of English alphabet.   Below tricks are covered in this post – Trick 1. Convert uppercase character to lowercase Trick 2. Convert lowercase character to uppercase Trick 3. Invert alphabet’s case Trick 4. Find letter’s position in alphabet     Trick 1. …

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## Bit Hacks – Part 3 (Playing with rightmost set bit of a number)

In this post we will discuss few related problems that are related to unsetting the rightmost set bit of a number.   How to unset the rightmost set bit of a number? The expression (n & (n – 1)) will turn off the rightmost set bit of given number. (n – 1) will have all …

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## Bit Hacks – Part 2 (Playing with k’th bit)

In this post we will discuss few related problems that operates on the k’th bit of a number.   Below problems are covered in this post – Problem 1. Turn off kth bit in a number Problem 2. Turn on kth bit in a number Problem 3. Check if kth bit is set for a …

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