Inserting integer into array using 1 for loop

Question

I am trying to write a method that takes a sorted array and an integer, and returns a new sorted array with the integer in the correct place.

I am trying to do this without using dynamic arrays, as well as only using 1 for loop - I have this working using a different method.

This is the method :

public static int[] insert(int[] a, int k) {
    int j = 0;
    int[] s = new int[a.length + 1];
    for(int i = 0; i < a.length; i++) {
        if(k < a[i] && j == 0) {
            s[i] = k;
            j++;
        } else {
            s[i + j] = a[i];
        }
    }
    return s;
}

My test input is

int[] array1 = new int[]{1, 2, 3, 4, 6, 7, 8};

and I am trying to insert a 5.

The issue I am having with this particular method is that it will always set the index after the inserted integer to 0. In this case it would store and print

1, 2, 3, 4, 5, 0, 7, 8

rather than

1, 2, 3, 4, 5, 6, 7, 8

Thanks

how it will print 4 there is no 4 in your array1? and inserting 5 which is already present in your array1. — Rustam
– Rustam, Commented Sep 22, 2015 at 5:48
just add s[i + j]=a[i]; inside your if after j++ to copy the value at inserted position . or simply remove else part — Rustam
– Rustam, Commented Sep 22, 2015 at 5:57

sprinter · Accepted Answer · 2015-09-22 05:58:34Z

2

It's not setting the index to zero, it's just jumping over one index. When k < a[i] is true it's incrementing i (in the for loop) and j (in j++ statement). So when you next do s[i + j] = a[i] it will have skipped two positions rather than one.

The solution is to ensure that in every iteration of the loop a value from the original array is copied. In other words, once you've assigned k to s[i] you then need to assign a[i] to s[i + 1]. The simplest way to achieve this is to remove your else clause and execute s[i + j] every iteration.

edited Sep 22, 2015 at 5:58

answered Sep 22, 2015 at 5:50

sprinter

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3 Comments

Arthur Over a year ago

You're right, any idea on how to make it only skip 1 index then? I tried s[i] = a[i] before, and obviously I just end up with duplicates of my insert.

sprinter Over a year ago

yep I'll put some hints in the answer

Arthur Over a year ago

turns out the 'else' was causing the skip, hmm

Louie11 · Accepted Answer · 2015-09-22 06:07:11Z

0

You may want to use an alternative. Instead of using a loop, use the Arrays object to add and sort your array.

Example:

public int[] insert(int[] a, int k) {
    // create a copy of int array parameter and add one to the length
    int[] s = Arrays.copyOf(a, a.length + 1);

    // add the second parameter at the end of the new array
    s[s.length - 1] = k;

    // sort the array
    Arrays.sort(s);

    return s;
}

answered Sep 22, 2015 at 6:07

Louie11

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Comments

Ankit Deshpande · Accepted Answer · 2015-09-22 06:19:39Z

0

   public static int[] insertIntoSortedArray(int[] array, int k) {
    int[] newArray = new int[array.length + 1];
    int i = 0;// for array
    int j = 0;// for new array
    boolean inserted = false;
    while (i < array.length) {
        if (!inserted && k < array[i]) {
            newArray[j] = k;
            inserted = true;
        } else {
            newArray[j] = array[i++];
        }
        j++;
    }
    return newArray;
}

answered Sep 22, 2015 at 6:19

Ankit Deshpande

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