Coding the Josephus Problem solution2.js

solution2.js

let nearestLowerPow2 = function (x) {
  if (x == 0) return 0;
  const arr = [1, 2, 4, 8, 16];
  arr.forEach(function(n) {
    x |= (x >> n);
  });

  return x - (x >> 1);
}

// Second solution based on the formula
const solution2 = (n) => {
  let lowPow2 = nearestLowerPow2(n);
  return 2*(n-lowPow2)+1;
};

const position = solution2(5);
console.log(position); // >>> 3