Solution to https://blog.svpino.com/2015/05/17/programming-challenge-merging-overlapping-intervals

overlappingIntervals.js

/*
  Solution to:
  https://blog.svpino.com/2015/05/17/programming-challenge-merging-overlapping-intervals
*/

function combineOverlappingIntervals(intervals){
  
  var overlapping = [], newOnes = [];

  // Compare each interval with every other interval
  intervals.forEach(function(x){
    intervals.forEach(function(y){
      // Don't compare with itself
      if(x===y){return;}
      // Check if overlap (easier math to calculate when 
      // not overlapping, so use this and negate)
      var overlap = !(x[0] > y[1] || y[0] > x[1]);
      // If overlapping and not detected already
      if(overlap && overlapping.indexOf(x) < 0){
        // Store overlapping intervals
        overlapping.push(x,y);
        // Create new interval
        newOnes.push([Math.min(x[0],y[0]),Math.max(x[1],y[1])]);
      }
    });
  });

  // Loop through original intervals, find those
  // that aren't overlapping and include them too
  intervals.forEach(function(x){
    overlapping.indexOf(x) < 0 && newOnes.push(x);
  });

  return newOnes;
}

// Test
combineOverlappingIntervals([
  [1,7],
  [2,8],
  [13,15],
  [14,16],
  [28,35]
]);