Register for our webinar

How to Nail your next Technical Interview

1 hour
Loading...
1
Enter details
2
Select webinar slot
*Invalid Name
*Invalid Name
By sharing your contact details, you agree to our privacy policy.
Step 1
Step 2
Congratulations!
You have registered for our webinar
check-mark
Oops! Something went wrong while submitting the form.
1
Enter details
2
Select webinar slot
*All webinar slots are in the Asia/Kolkata timezone
Step 1
Step 2
check-mark
Confirmed
You are scheduled with Interview Kickstart.
Redirecting...
Oops! Something went wrong while submitting the form.
close-icon
Iks white logo

You may be missing out on a 66.5% salary hike*

Nick Camilleri

Head of Career Skills Development & Coaching
*Based on past data of successful IK students
Iks white logo
Help us know you better!

How many years of coding experience do you have?

Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
Iks white logo

FREE course on 'Sorting Algorithms' by Omkar Deshpande (Stanford PhD, Head of Curriculum, IK)

Thank you! Please check your inbox for the course details.
Oops! Something went wrong while submitting the form.
closeAbout usWhy usInstructorsReviewsCostFAQContactBlogRegister for Webinar
Our June 2021 cohorts are filling up quickly. Join our free webinar to Uplevel your career
close

Implement Merge Sort Problem

Implement Merge Sort Problem Statement

Given a list of numbers, sort it using the Merge Sort algorithm.

Example

{
"arr": [5, 8, 3, 9, 4, 1, 7]
}

Output:

[1, 3, 4, 5, 7, 8, 9]

Notes

Constraints:

  • 1 <= length of the given list <= 105
  • -109 <= number in the list <= 109

Explanation: https://www.interviewkickstart.com/learn/merge-sort

Implement Merge Sort Solution 1: Iterative

Code For Implement Merge Sort Solution 1: Iterative

    /*
    Asymptotic complexity in terms of size of \`arr\` \`n\`:
    * Time: O(n * log(n)).
    * Auxiliary space: O(n).
    * Total space: O(n).
    */
    static ArrayList<Integer> merge_sort(ArrayList<Integer> arr) {
        int n = arr.size();
        int left = 0, right = n - 1;
        split(arr, left, right);
        return arr;
    }

    static void split(List<Integer> arr, int l, int h) {
        // divide the array into blocks of size [1, 2, 4, 8, ..]
        for (int blocks = 1; blocks <= h - l; blocks = 2 * blocks) {
            // for blocks = 1, i = 0, 2, 4, 6, 8 and so on
            // for each block we split the array into sub arrays and merge them
            /* note that each of these subarrays will always be sorted as we are
             building the array from smaller subarrays to larger subarrays*/
            for (int i = l; i < h; i += 2 * blocks) {
                int left = i;
                int mid = Math.min(i + blocks - 1, h);
                int right = Math.min(i + 2 * blocks - 1, h);
                merge(arr, left, mid, right);
            }
        }
    }

    /*function to merge 2 sorted arrays*/
    static void merge(List<Integer> arr, int left, int mid, int right) {
        int[] l = new int[mid - left + 1];
        //copies the integers to array l from arr
        for(int i = 0; i < mid - left + 1; i++) {
            l[i] = arr.get(left + i);
        }
        int[] r = new int[right - mid];
        //copies the integers to array r from arr
        for(int i = 0; i < right - mid; i++) {
            r[i] = arr.get(mid + i + 1);
        }
        int i = 0, j = 0, k = left;
        //merges arrays l and r back to arr
        while(i < l.length && j < r.length) {
            if(l[i] <= r[j]) {
                arr.set(k, l[i]);
                i++;
            }
            else {
                arr.set(k, r[j]);
                j++;
            }
            k++;
        }
        //merges remaining elements of arrays l and r
        while(i < l.length) {
            arr.set(k++, l[i++]);
        }
        while(j < r.length) {
            arr.set(k++, r[j++]);
        }
    }

Implement Merge Sort Solution 2: Recursive

Code For Implement Merge Sort Solution 2: Recursive

    /*
    Asymptotic complexity in terms of size of \`arr\` \`n\`:
    * Time: O(n * log(n)).
    * Auxiliary space: O(n).
    * Total space: O(n).
    */
    static ArrayList<Integer> merge_sort(ArrayList<Integer> arr) {
        int n = arr.size();
        int left = 0, right = n - 1;
        split(arr, left, right);
        return arr;
    }

    /*function to partition the array into subarrays and then merge them*/
    static void split(List<Integer> arr, int left, int right) {
        if(left < right) {
            int mid = (left + right) / 2;
            //sort first and second halves of the array
            split(arr, left, mid);
            split(arr, mid + 1, right);
            //merge the sorted halves
            merge(arr, left, mid, right);
        }
    }

    /*function to merge 2 sorted arrays*/
    static void merge(List<Integer> arr, int left, int mid, int right) {
        int[] l = new int[mid - left + 1];
        //copies the integers to array l from arr
        for(int i = 0; i < mid - left + 1; i++) {
            l[i] = arr.get(left + i);
        }
        int[] r = new int[right - mid];
        //copies the integers to array r from arr
        for(int i = 0; i < right - mid; i++) {
            r[i] = arr.get(mid + i + 1);
        }
        int i = 0, j = 0, k = left;
        //merges arrays l and r back to arr
        while(i < l.length && j < r.length) {
            if(l[i] <= r[j]) {
                arr.set(k, l[i]);
                i++;
            }
            else {
                arr.set(k, r[j]);
                j++;
            }
            k++;
        }
        //merges remaining elements of arrays l and r
        while(i < l.length) {
            arr.set(k++, l[i++]);
        }
        while(j < r.length) {
            arr.set(k++, r[j++]);
        }
    }

We hope that these solutions to merge sort problem have helped you level up your coding skills. You can expect problems like these at top tech companies like Amazon and Google.

If you are preparing for a tech interview at FAANG or any other Tier-1 tech company, register for Interview Kickstart's FREE webinar to understand the best way to prepare.

Interview Kickstart offers interview preparation courses taught by FAANG+ tech leads and seasoned hiring managers. Our programs include a comprehensive curriculum, unmatched teaching methods, and career coaching to help you nail your next tech interview.

We offer 18 interview preparation courses, each tailored to a specific engineering domain or role, including the most in-demand and highest-paying domains and roles, such as:

‍To learn more, register for the FREE webinar.

Try yourself in the Editor

Note: Input and Output will already be taken care of.

Implement Merge Sort Problem

Implement Merge Sort Problem Statement

Given a list of numbers, sort it using the Merge Sort algorithm.

Example

{
"arr": [5, 8, 3, 9, 4, 1, 7]
}

Output:

[1, 3, 4, 5, 7, 8, 9]

Notes

Constraints:

  • 1 <= length of the given list <= 105
  • -109 <= number in the list <= 109

Explanation: https://www.interviewkickstart.com/learn/merge-sort

Implement Merge Sort Solution 1: Iterative

Code For Implement Merge Sort Solution 1: Iterative

    /*
    Asymptotic complexity in terms of size of \`arr\` \`n\`:
    * Time: O(n * log(n)).
    * Auxiliary space: O(n).
    * Total space: O(n).
    */
    static ArrayList<Integer> merge_sort(ArrayList<Integer> arr) {
        int n = arr.size();
        int left = 0, right = n - 1;
        split(arr, left, right);
        return arr;
    }

    static void split(List<Integer> arr, int l, int h) {
        // divide the array into blocks of size [1, 2, 4, 8, ..]
        for (int blocks = 1; blocks <= h - l; blocks = 2 * blocks) {
            // for blocks = 1, i = 0, 2, 4, 6, 8 and so on
            // for each block we split the array into sub arrays and merge them
            /* note that each of these subarrays will always be sorted as we are
             building the array from smaller subarrays to larger subarrays*/
            for (int i = l; i < h; i += 2 * blocks) {
                int left = i;
                int mid = Math.min(i + blocks - 1, h);
                int right = Math.min(i + 2 * blocks - 1, h);
                merge(arr, left, mid, right);
            }
        }
    }

    /*function to merge 2 sorted arrays*/
    static void merge(List<Integer> arr, int left, int mid, int right) {
        int[] l = new int[mid - left + 1];
        //copies the integers to array l from arr
        for(int i = 0; i < mid - left + 1; i++) {
            l[i] = arr.get(left + i);
        }
        int[] r = new int[right - mid];
        //copies the integers to array r from arr
        for(int i = 0; i < right - mid; i++) {
            r[i] = arr.get(mid + i + 1);
        }
        int i = 0, j = 0, k = left;
        //merges arrays l and r back to arr
        while(i < l.length && j < r.length) {
            if(l[i] <= r[j]) {
                arr.set(k, l[i]);
                i++;
            }
            else {
                arr.set(k, r[j]);
                j++;
            }
            k++;
        }
        //merges remaining elements of arrays l and r
        while(i < l.length) {
            arr.set(k++, l[i++]);
        }
        while(j < r.length) {
            arr.set(k++, r[j++]);
        }
    }

Implement Merge Sort Solution 2: Recursive

Code For Implement Merge Sort Solution 2: Recursive

    /*
    Asymptotic complexity in terms of size of \`arr\` \`n\`:
    * Time: O(n * log(n)).
    * Auxiliary space: O(n).
    * Total space: O(n).
    */
    static ArrayList<Integer> merge_sort(ArrayList<Integer> arr) {
        int n = arr.size();
        int left = 0, right = n - 1;
        split(arr, left, right);
        return arr;
    }

    /*function to partition the array into subarrays and then merge them*/
    static void split(List<Integer> arr, int left, int right) {
        if(left < right) {
            int mid = (left + right) / 2;
            //sort first and second halves of the array
            split(arr, left, mid);
            split(arr, mid + 1, right);
            //merge the sorted halves
            merge(arr, left, mid, right);
        }
    }

    /*function to merge 2 sorted arrays*/
    static void merge(List<Integer> arr, int left, int mid, int right) {
        int[] l = new int[mid - left + 1];
        //copies the integers to array l from arr
        for(int i = 0; i < mid - left + 1; i++) {
            l[i] = arr.get(left + i);
        }
        int[] r = new int[right - mid];
        //copies the integers to array r from arr
        for(int i = 0; i < right - mid; i++) {
            r[i] = arr.get(mid + i + 1);
        }
        int i = 0, j = 0, k = left;
        //merges arrays l and r back to arr
        while(i < l.length && j < r.length) {
            if(l[i] <= r[j]) {
                arr.set(k, l[i]);
                i++;
            }
            else {
                arr.set(k, r[j]);
                j++;
            }
            k++;
        }
        //merges remaining elements of arrays l and r
        while(i < l.length) {
            arr.set(k++, l[i++]);
        }
        while(j < r.length) {
            arr.set(k++, r[j++]);
        }
    }

We hope that these solutions to merge sort problem have helped you level up your coding skills. You can expect problems like these at top tech companies like Amazon and Google.

If you are preparing for a tech interview at FAANG or any other Tier-1 tech company, register for Interview Kickstart's FREE webinar to understand the best way to prepare.

Interview Kickstart offers interview preparation courses taught by FAANG+ tech leads and seasoned hiring managers. Our programs include a comprehensive curriculum, unmatched teaching methods, and career coaching to help you nail your next tech interview.

We offer 18 interview preparation courses, each tailored to a specific engineering domain or role, including the most in-demand and highest-paying domains and roles, such as:

‍To learn more, register for the FREE webinar.

Worried About Failing Tech Interviews?

Attend our free webinar to amp up your career and get the salary you deserve.

Ryan-image
Hosted By
Ryan Valles
Founder, Interview Kickstart
blue tick
Accelerate your Interview prep with Tier-1 tech instructors
blue tick
360° courses that have helped 14,000+ tech professionals
blue tick
100% money-back guarantee*
Register for Webinar

Recommended Posts

All Posts