how to find largest elements from the sorted array?

Question

I have three sorted array I need to find top five "5" element from these array .I am able to find first two element largest element .how I will find other ?

can you suggest how we can find other 3 element ?

here is my code

 var maxArray=[];
        var array1=[2,7,12,23,40,44,67,88,102]
        var array2=[3,12,14,17,23,40,41,67,108]
        var array3=[8,12,23,40,59,86,119,130]
        var firstMax=array1[array1.length-1];
        var secondMax=array2[array2.length-1];


        alert(array1[array1.length-1]);
        if(array1[array1.length-1]>array2[array2.length-1] && array1[array1.length-1]>array3[array3.length-1]){

            maxArray.push(array1[array1.length-1]) ;
            firstMax=array1[array1.length-1];
            if(array2[array2.length-1]>array3[array3.length-1]){
                secondMax=array2[array2.length-1];
            }else {
                secondMax=array3[array3.length-1];

            }
        }else if(array2[array2.length-1]>array1[array1.length-1]&& array2[array2.length-1]>array3[array3.length-1]){
            maxArray.push(array1[array2.length-1])
            firstMax=array2[array2.length-1];

            if(array1[array1.length-1]>array3[array3.length-1]){
                secondMax=array1[array1.length-1];
            }else {
                secondMax=array3[array3.length-1];

            }

        }else{
            maxArray.push(array3[array3.length-1])
            firstMax=array3[array3.length-1];

            if(array2[array2.length-1]>array1[array1.length-1]){
                secondMax=array2[array2.length-1];
            }else {
                secondMax=array1[array1.length-1];

            }

        }
        maxArray.push(secondMax)

        alert(maxArray)

fiddle http://jsfiddle.net/9vsjm8uh/

wouldn't it just be easier to create a single merged array, sort that, then pop off the final 5 elements? — Marc B
– Marc B, Commented Sep 3, 2014 at 17:03
@MarcB Well that's the idea, isn't it? Merge the arrays in descending order and stop when you hit 5 elements in the merged array? — beaker
– beaker, Commented Sep 3, 2014 at 17:06
yeah, but OP's doing a hell of a lot of extra work instead of a basic pop_5((array1 + array2 + array3).sort()) (pseudo code, of course) — Marc B
– Marc B, Commented Sep 3, 2014 at 17:07
hi thanks for answer why this function used inside the sort function function sortNumber(a, b) { return a - b; } — Shruti
– Shruti, Commented Sep 3, 2014 at 17:40

Benny Bottema · Accepted Answer · 2014-09-03 19:11:01Z

2

jsFiddle (yep, even better without jQuery, thanks @Rajacsp)

var array1 = [2, 7, 12, 23, 40, 44, 67, 88, 102]
var array2 = [3, 12, 14, 17, 23, 40, 41, 67, 108]
var array3 = [8, 12, 23, 40, 59, 86, 119, 130]

var flatArray = array1.concat(array2).concat(array3);

flatArray.sort(function sortNumber(a, b) { return b - a; });
var maxArray = flatArray.slice(0, 5);

alert(maxArray); // 130,119,108,102,88

edited Sep 3, 2014 at 19:11

answered Sep 3, 2014 at 17:10

Benny Bottema

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5 Comments

Swetha Over a year ago

Use var maxArray = flatArray.slice(0, 5); to extract top 5 elements.

Raja CSP Over a year ago

@Plantface, why don't you stick with Jquery lib? I would have got some votes :-)

Shruti Over a year ago

hi thanks for answer why this function used inside the sort function function sortNumber(a, b) { return a - b; }

Benny Bottema Over a year ago

@user2535959 If you leave that out, then it will use 'natural' sort order, meaning alphabetical. Numbers won't sort correctly in that case as the default sort function takes into account the length of the numbers.

Raja CSP Over a year ago

@Plantface, I just edited the code to do the inverse sorting!

jj172 · Accepted Answer · 2014-09-03 17:09:34Z

0

I would suggest the following idea:

Since you are looking for the top 5 values, they will, at worst case, all be in the same list. Thus, there are at most 5 * 3 = 15 values to check.

Then, you can take the 5 highest values from each list (which should be trivial if the list is already sorted), and then put them in another list. Now you have a list of the 15, and you want to find the top 5 values from this list. There are different ways to do this - you could sort the list, then take the top 5 values, or you can simply iterate through the list, finding the max each time.

answered Sep 3, 2014 at 17:09

jj172

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Comments

Michael Sacks · Accepted Answer · 2014-09-03 17:14:50Z

0

Combine all of the arrays, sort them, then get the last 5 values.

var total = array1.concat(array2, array3);
total = total.sort(function(a,b){return a-b});
//Now total[length-5] is the 5th largest value
//total[length-4] is the 4th largest and so on

answered Sep 3, 2014 at 17:14

Michael Sacks

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2 Comments

Michael Sacks Over a year ago

note that the sort parameters ensure that the values are sorted in order (i.e. 2,3,7,8,12,12 etc. instead of .sort() which returns 12,12,12,2,3,7,8 because it sorts by the first digit).

Felix Kling Over a year ago

You can't concatenate arrays with +. This is not PHP.

Raja CSP · Accepted Answer · 2014-09-03 18:01:47Z

0

Plain Javascript (no libraries added):

var array1=[2,7,12,23,40,44,67,88,102];
var array2=[3,12,14,17,23,40,41,67,108];
var array3=[8,12,23,40,59,86,119,130];


alert(getTopFive(array1, array2, array3));

function getTopFive(ar1, ar2, ar3){
    var finalArray = array1.concat(array2).concat(array3);
    finalArray.sort(function sortInverse(a,b) { return b - a; });
    return finalArray.slice(0, 5);  
}

edited Sep 3, 2014 at 18:01

answered Sep 3, 2014 at 17:20

Raja CSP

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2 Comments

Benny Bottema Over a year ago

come now, that could have been a nice suggestion on the other answer :D

Shruti Over a year ago

hi thanks for answer why this function used inside the sort function function sortInverse(a, b) { return a - b; }

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