edaBit-coding-challenges/Bit-Rotation/code.cpp

/*  C++ offers some bit operations but not bit rotation. To complete that,
 *  create a function that takes three parameters:
 *  n: Integer, which in binary representaion should be rotated.
 *  m: Number of rotation steps that should be performed.
 *  d: Boolean value; true = rotation right, false = rotation left.
 *  Your function should return an integer as a result of its rotated
 *  binary representation.
 *  bitRotate(8, 1, true) ➞ 4
 *  8 in bin: 1000, rotated 1 step to the right: 0100, in dec: 4
 *  For parameters use unsigned integers only.
 */
int bitRotate(int n, int m, bool d) {
    int p = n, c = 1, b = 1;
    //  find the power of the input
    while(p/=2) c++;
    //  short circuit if power and rotations are the same
    if(c==m)return n;
    //  set the bracket for the input
    b<<=c;b--;
  //  check each rotation to see if over the bracket and rotate  
	for(int i = 0;i<m;i++){
        if(d /*right*/){
           if(n&1) n += (b+1); n >>= 1;
        } else /*left*/ {
            n <<= 1; if(n>b) n -= b;
        }
    }
    return n;
    //  return d? n<<m : n>>m; <<== should be as simple as this
}