Bit Manipulation - Useful Tricks for efficient coding.

1. Create a number that has only set bit as k-th bit --> 1 << (k-1)
2. Check whether k-th bit is set or not -->

   if (n & (1 << (k - 1)))
       cout << "SET";
3. Set k-th bit to 1 --> n | (1 << (k - 1))
4. Clearing the k-th bit --> n & ~(1 << (k - 1))
5. Toggling the k-th bit --> n ^ (1 << (k – 1))
6. Check whether n is power of 2 or not

   if(x && (!( x&(x-1) ))
   cout<<"Power of 2";
7. (x<<y) is equivalent to multiplying x with 2^y (2 raised to power y).
8. (x>>y) is equivalent to dividing x with 2^y.
9. Swapping two numbers

   x = x ^ y
   y = x ^ y
   x = x ^ y
10. Average of two numbers --> (x+y) >> 1
11. Convert character ch from Upper to Lower case --> ch = ch | ' '
12. Convert character ch from Lower to Upper case -->ch = ch & '_'
13. Check if n is odd or even -->

    if(n & 1)
    cout<<"odd"
    else
    cout<<"even";

Bitwise operations are very useful as they mostly operate in O(1) time.
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