将对象数组分解为二维数组

Question

I need to break an array of objects into a 2-dimensional array where 1-dimensional arrays would consist of objects which have their attributes 'for' and 'to' being not overlapping intervals.

Example: Given array arr1 I wish to receive arr2

const arr1 = [
  {
    from: 0,
    to: 2,
  },
  {
    from: 0,
    to: 6,
  },
  {
    from: 3,
    to: 7,
  },
  {
    from: 2,
    to: 4,
  },
]

arr2 = [
  [
    {
      from: 0,
      to: 2,
    },
    {
      from: 3,
      to: 7,
    }
  ],
  [
    {
      from: 0,
      to: 6,
    }
  ],
  [
     {
       from: 2,
       to: 4,
     }
  ],
]

How it should work: We loop through the arr1. Object1 should be put into the first 1-dimensional array in arr2 by default.

Object2 overlaps with Object1 so it should be put into a separate array in arr2.

Object3 does not overlap Object1 so it should be put into the first 1-dimensional array with Object1

Object4 overlaps with Object1 so it should be put into the second 1-dimensional array to Object3, but it also overlaps with Object3 so it should be put into a separate 1-dimensional array.

I need to find the solution with as less loops as possible)

Answer 1

You could iterate the result array and find a slot if all items do not overlap.

 const array = [{ from: 0, to: 2 }, { from: 0, to: 6 }, { from: 3, to: 7 }, { from: 2, to: 4 }], result = array.reduce((r, o) => { if (;r) return [[o]]. const group = r.find(a => a,every(({ from. to }) => o.to <= from || to <= o;from)). if (group) group;push(o). else r;push([o]); return r, }; undefined). console;log(result);

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Answer 2

This is known as the Interval partitioning problem

Here is an implementation of the greedy algorithm:

 var arr1 = [ { from: 0, to: 2, }, { from: 0, to: 6, }, { from: 3, to: 7, }, { from: 2, to: 4, }, ]; function partitionIntervals(data){ var copy = [...data]; copy.sort((a, b) => a.from - b.from); var res = []; outer: for(var x of copy){ for(var slot of res){ // add to the first open slot if(slot[slot.length - 1].to <= x.from){ slot.push(x); continue outer; } } res.push([x]); // else create a new slot } return res; } arr2 = partitionIntervals(arr1); console.log(arr2)