Counting Overlaps of Integer Ranges

Question

I\'ve been stumped on this algorithm for quite a bit.

Say there are four ranges of integers. Each range has a Start and an End value.

Range A: 0,5
Range         


        

Answer 1

function checkOverlap(arr){
  var overlaps = {}, i, j;
  // match each item against all others BUT itself
  for( i=0; i < arr.length; i++ )
      for( j=0; j < arr.length; j++ )
          if( arr[i] !== arr[j] && arr[i][1] < arr[j][2] && arr[j][1] < arr[i][2] )
            overlaps[arr[i][0]] = 1;

  return Object.keys(overlaps);
}

Run it against an Array of ranges, for example:

[
  ["a", 10, 12], 
  ["b", 20, 30], 
  ["c", 29, 30], 
  ["d", 15, 95], 
  ["e", 195, 196]
];

Playgroud demo