Count the number of set bits (1s) in binary representation of an integer public int CountSetBits(int n) { int count = 0; while (n != 0) { count += n & 1; n >>= 1; } return count; } Explanation: Shift through each bit; add 1 to count if least significant bit is set.

Short answer: lternative using Brian Kernighan’s algorithm: public int CountSetBits(int n) { int count = 0; while (n != 0) { n &= (n - 1); // Drops the lowest set bit count++; } return count; } Follow on: lternative using Brian Kernighan’s algorithm: public int CountSetBits(int n) { int count = 0; while (n != 0) { n &= (n - 1); // Drops… the lowest set bit…… lternative using Brian Kernighan’s algorithm: public int…

Explain a bit more

CountSetBits(int n) { int count = 0; while (n != 0) { n &= (n - 1); // Drops the lowest set bit count++; } return count; } Follow on: lternative using Brian Kernighan’s algorithm: public int CountSetBits(int n) { int count = 0; while (n != 0) { n &= (n - 1); // Drops… the lowest set bit count++; } return count; } Follow on:

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.