CODEWITHSUNDEEP
javascriptjqueryarraysalgorithm
alexey
alexey

Reputation: 801

Get first minimum free integer key/id in array of integer

Suppose i have some key array:

var idlist= [1, 2, 3, 6];

after I was created new object, I need new key/id for it, so i need somethink like this:

fucntion getFirstFreeKey(keylist){
???
}

in my example getFirstFreeKey(idlist) will return 4.

Upvotes: 1

Views: 881

Answers (2)

Nina Scholz
Nina Scholz

Reputation: 386540

This proposal works with Array#every()

The every() method tests whether all elements in the array pass the test implemented by the provided function.

The algorithm looks for consecutive numbers and returns the last one, incremented by one, if a gap is found.

function free(array, start) {
    array.every(function (a) {
        if (start === a) {
            start = a + 1;
            return true;
        }
    });
    return start;
}

document.write(free([1, 2, 3, 6], 1) + '<br>'); // 4
document.write(free([1, 2, 3, 4], 1) + '<br>'); // 5
document.write(free([2, 3, 4], 1) + '<br>');    // 1
document.write(free([], 1) + '<br>');           // 1

Upvotes: 3

Appelman
Appelman

Reputation: 126

Assuming your list is ordered and you need the next free sequential number:

var freeNum;

for(var i = 0; i < idlist.Length; i++)
{
    if(idList[i] != i + 1)
    {
         freeNum = i + 1;
         break;
    }
}

return freeNum;

Upvotes: 0

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