计算时间范围与时间范围的重叠

Question

I try to calculate the amount (in minutes) of overlaps between a given time range and an array of time ranges.

First I order the ranges by start time, and filter them, if they not overlap with the range.

 const range = ["2019-11-06 08:00", "2019-11-06 17:00"]; // 9h const ranges = [ ["2019-11-06 00:00", "2019-11-06 10:00"], ["2019-11-06 22:00", "2019-11-06 24:00"], ["2019-11-06 09:00", "2019-11-06 12:00"] ] function calculateOvelappings(range, ranges) { const start = moment(range[0]) const end = moment(range[1]) let overlaps = 0 // order ranges by start time ranges = ranges.sort((a, b) => moment(a[0]).unix() - moment(b[0]).unix()) for(let i = 0; i < ranges.length; i++) { const rangeStart = moment(ranges[i][0]) const rangeEnd = moment(ranges[i][1]) if (rangeEnd.isBefore(start) || rangeStart.isAfter(end)) { continue; } } return overlaps } console.log(calculateOvelappings(range, ranges))

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EDIT

The right answer for overlaps would be 4 hours. The input range starts at 08:00 in intersects with range 1 (from the array) till 10:00 (2 hours). Range 2 is irrelevant. Range 3 overlaps with the input range from 09:00 to 12:00, but from 09:00 to 10:00 is already calculated from range 1. Therefor 2 + (3 - 1) = 4 hours.

Is there an elegant algorithm, to calculate this? Any help would be appreciated, a pseudo code, or even a theoretical answare.

Here is a JsBin: https://jsbin.com/noyuhekura/1/edit?js,console

Answer 1

 const range = ["2019-11-06 08:00", "2019-11-06 17:00"]; // 9h const ranges = [ ["2019-11-06 00:00", "2019-11-06 10:00"], ["2019-11-06 22:00", "2019-11-06 24:00"], ["2019-11-06 09:00", "2019-11-06 12:00"] ] function calculateOvelappings(range, ranges) { const start = moment(range[0]) const end = moment(range[1]) let overlaps = 0 // order ranges by start time ranges = ranges.sort((a, b) => moment(a[0]).unix() - moment(b[0]).unix()) for(let i = 0; i < ranges.length; i++) { const rangeStart = moment(ranges[i][0]) const rangeEnd = moment(ranges[i][1]) if (rangeEnd.isBefore(start) || rangeStart.isAfter(end)) { continue; } overlaps += rangeEnd - rangeStart // Updated } return overlaps } console.log(calculateOvelappings(range, ranges))

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Answer 2

you haven't updated overlaps at all. You need to add:

overlaps += (rangeEnd - rangeStart)

otherwise it never changes from 0