Algorithm for finding overlapping events/times

Question

While working on custom calendar, I can\'t figure out how to find time slots that overlaps any other time slot.

Time slots start from 0 to 720 (9am to 9pm with each

Answer 1

from my jquery-week-calendar commit, this is how i do it:

    _groupOverlappingEventElements: function($weekDay) {
        var $events = $weekDay.find('.wc-cal-event:visible');
        var complexEvents = jQuery.map($events, function (element, index) {
            var $event = $(element);
            var position = $event.position();
            var height = $event.height();
            var calEvent = $event.data('calEvent');
            var complexEvent = {
                'event': $event,
                'calEvent': calEvent,
                'top': position.top,
                'bottom': position.top + height
            };
            return complexEvent;
        }).sort(function (a, b) {
            var result = a.top - b.top;
            if (result) {
                return result;
            }
            return a.bottom - b.bottom;
        });
        var groups = new Array();
        var currentGroup;
        var lastBottom = -1;
        jQuery.each(complexEvents, function (index, element) {
            var complexEvent = element;
            var $event = complexEvent.event;
            var top = complexEvent.top;
            var bottom = complexEvent.bottom;
            if (!currentGroup || lastBottom < top) {
                currentGroup = new Array();
                groups.push(currentGroup);
            }
            currentGroup.push($event);
            lastBottom = Math.max(lastBottom, bottom);
        });
        return groups;
    }

there's a bit of component-specific noise around, but you'll get the logic:

• sort the events by their starting ascending
• sort the events by their ending ascending
• iterate over the sorted events and check the starting/ending of the previous event (done rather by position, than by the event properties themself - just because the design might overlap, but the events not ... eg: making a border 2px, events with not overlapping start/end-times might overlap or "touch")
• each overlapping-group (currentGroup) is a new array inside the groups-array

soo ... your code might look sth alike this (btw, no need to work with the real date-instances)

events.sort(function (a, b) {
    var result = a.start - b.start;
    if (result) {
        return result;
    }
    return a.end - b.end;
});
var groups = new Array();
var currentGroup;
var lastEnd = -1;
jQuery.each(events, function (index, element) {
    var event = element;
    var start = event.start;
    var end = event.end;
    if (!currentGroup || lastEnd < start) {
        currentGroup = new Array();
        groups.push(currentGroup);
    }
    currentGroup.push(event);
    lastEnd = Math.max(lastEnd, end);
});
return groups;

soo ... you are not willed to push some own energy into your problem ... well

var output = new Array();
jQuery.each(groups, function (index, element) {
    var group = element;
    if (group.length <= 1) {
        return;
    }
    jQuery.each(group, function (index, element) {
        var event = element;
        var foo = {
            'id': event.id,
            'eventCount': group.length
        };
        output.push(foo);
    });
});