title: What is the fastest way to find the closest point to a given point?
body: <p>What is the fastest way to find closest point to the given point in data array?</p>
  
  <p>For example, suppose I have an array <code>A</code> of 3D points (with coordinates x, y and z, as usual) and point (x_p, y_p, z_p). How do I find the closest point in <code>A</code> to (x_p, y_p, z_p)?</p>
  
  <p>As far as I know, slowest way to do it is to use linear search. Are there any better solutions? </p>
  
  <p>Addition of any an auxiliary data structure is possible.</p>