Bit Manipulation and Mathematical Reasoning Flashcards
6 cards from real CodeSignal Technical Assessment practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Bit Manipulation and Mathematical Reasoning flashcards as text
What does the expression `n & (n-1)` evaluate to when n is a power of 2?
Answer: 0
A power of 2 has exactly one set bit; subtracting 1 flips all lower bits, so ANDing gives 0.
How do you check if the k-th bit (0-indexed) of integer n is set?
Answer: n & (1 << k)
Shifting 1 left by k positions creates a mask; ANDing with n isolates that bit, giving a non-zero result if it is set.
What is 5 XOR 3 in decimal?
Answer: 6
5 is 101 and 3 is 011 in binary; XOR gives 110, which equals 6 in decimal.
What does left-shifting an integer n by 1 position (`n << 1`) effectively compute?
Answer: n * 2
Left-shifting by 1 appends a zero bit on the right, which doubles the value in base-2 representation.
Which bit trick isolates the lowest set bit of integer n?
Answer: n & (-n)
The two's complement of n (-n) flips all bits and adds 1, so n & (-n) keeps only the rightmost set bit.
What is the result of `n ^ n` for any integer n?
Answer: 0
XORing any value with itself cancels every bit, producing 0.