Learn and practice the Merge Intervals and K-way Merge patterns to solve coding interview problems.

Speedrun the LinkedIn Coding Interview: Top JavaScript Problems

Many information processing and decision-support problems require us to merge information coming from multiple sources to build up a global picture of a situation before making some business decisions. This module will help us understand and deploy two common coding patterns used to merge lists of structurally homogeneous data to solve hard problems that we encounter, for example, in scheduling, social media applications, and I/O algorithms.

Fusion



**Constraints:**
- `nums1.length` $= m + n$
- `nums2.length` $= n$
- $0 \leq m, n \leq 200$
- $1 \leq m + n \leq 200$
- $-10^3 \leq$ `nums1[i]`, `nums2[j]` $\leq 10^3$

What is the output if the following arrays and values of $m$ and $n$ are given as input?

nums1 = [1, 2, 7, 92, 0, 0, 0], m = 4

nums2 = [3, 4, 5], n = 3

What is the output if the following arrays and values of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>m</mi></mrow><annotation encoding="application/x-tex">m</annotation></semantics></math>m and <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>n</mi></mrow><annotation encoding="application/x-tex">n</annotation></semantics></math>n are given as input?
nums1 = [1, 2, 7, 92, 0, 0, 0], m = 4
nums2 = [3, 4, 5], n = 3

What is the output if the following arrays and values of $m$ and $n$ are given as input?

nums1 = [0], m = 0

nums2 = [5], n = 1

What is the output if the following arrays and values of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>m</mi></mrow><annotation encoding="application/x-tex">m</annotation></semantics></math>m and <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>n</mi></mrow><annotation encoding="application/x-tex">n</annotation></semantics></math>n are given as input?
nums1 = [0], m = 0
nums2 = [5], n = 1

What is the output if the following arrays and values of $m$ and $n$ are given as input?

nums1 = [1, 12, 57, 98, 0, 0, 0, 0], m = 4

nums2 = [1, 4, 5, 57], n = 4

What is the output if the following arrays and values of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>m</mi></mrow><annotation encoding="application/x-tex">m</annotation></semantics></math>m and <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>n</mi></mrow><annotation encoding="application/x-tex">n</annotation></semantics></math>n are given as input?
nums1 = [1, 12, 57, 98, 0, 0, 0, 0], m = 4
nums2 = [1, 4, 5, 57], n = 4

What is the output if the following arrays and values of $m$ and $n$ are given as input?

nums1 = [2], m = 1

nums2 = [], n = 0

What is the output if the following arrays and values of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>m</mi></mrow><annotation encoding="application/x-tex">m</annotation></semantics></math>m and <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>n</mi></mrow><annotation encoding="application/x-tex">n</annotation></semantics></math>n are given as input?
nums1 = [2], m = 1
nums2 = [], n = 0

Merge Sorted Array

Merge Sorted Array

# Figure it out!
We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

# Try it yourself
Implement your solution in the following coding playground.

# Template for array traversal
class traversal:
    def __init__(self):
        self.array = []
        
    def forward_traversal(self):
        for element in self.array:
            print(element)
        
    def backward_traversal(self):
        for i in range(len(self.array) - 1, -1, -1):
            print(self.array[i])


# Quick Fix\nYou are Edward, a Senior Software Engineer who specializes in coding interview patterns, data structures and algorithms, and is great at debugging issues in code.\n\n- Edward, please keep in mind that you do not have to print the data of the placeholders. Also, do not mention anything about yourself.\n\nEdward, you are given the following data in the placeholders:\n- Function name: `mergeSorted`\n- Candidate's submitted solution code: USER_CODE\n- Error: ERROR_DESCRIPTION\n- Failed test case: FAILED_TEST_CASE\n- Coding language: `JavaScript`\n\n- Edward, your task is to understand the type of error that is occurring in the coding language provided.\n- Once you've understood the error as per the error’s description, and why the test case failed, you will suggest how the candidate can improve their solution code to fix the error.\n- Edward, you will not give the corrected code, just a hint on what the error tells, and how to fix it.\n- Edward, please limit your response strictly to 100 words. No more words than the limit.

# Review Code\nEdward, your current task is to review the `mergeSorted` function(s) and the other function(s) invoked in it/them.\n\n-Take your time and review the candidate's solution code.\n- Do not review any extra/helper files or functions not invoked in the solution function `mergeSorted`.\n- Do not review the code of data structure objects instantiated like a binary tree, linked list, trie, union find, etc., in the solution functions. Just review the solution/algorithm function of the problem. \n- Also, if the solution code doesn’t use the coding pattern stated above, then please encourage the candidate to reattempt the problem using that pattern corectly.

# Review time complexity\n- Please provide a brief time complexity analysis of the function(s) `mergeSorted`. \n- While calculating time complexity, include the time complexity of built-in JavaScript functions invoked by the code. \n- The answer should be to the point in approximately 60 words.

# Review space complexity\n- Please provide a brief space complexity analysis of the function(s) `mergeSorted`. \n- While calculating space complexity, include the space complexity of built-in JavaScript functions invoked by the code. \n- Do not include the space used for the input parameters and the space used for just returning an output (not used as a scratch space). \n- The answer should be to the point in approximately 60 words.

def evaluate_results(self) -> object:
 """
 self.__inputs is the list of inputs that are passed as input to function
 self.__actual_output is a list of outputs that is produced by the learner's code
 return : self.__edu__result object
 """
 def merge_sorted(nums1, m, nums2, n):
 p1 = m - 1 
 p2 = n - 1 
 x = 0
 for p in range(n + m - 1, -1, -1):
 if p2 < 0:
 break
 x += 1
 if p1 >= 0 and nums1[p1] > nums2[p2]:
 nums1[p] = nums1[p1]
 p1 -= 1
 else:
 nums1[p] = nums2[p2]
 p2 -= 1
 return nums1
 # multiple outputs will be added at each index respectively for a single test_case
 expected_outputs = []
 input1 = self.__inputs[0]
 input2 = self.__inputs[1]
 input3 = self.__inputs[2]
 input4 = self.__inputs[3]
 expected = merge_sorted(input1, input2, input3, input4)
 # store the 1st expected output that should be displayed to the user 
 expected_outputs.append(expected)
 actual = self.__actual_outputs[0]
 
 if json.dumps(expected) == json.dumps(actual):
 self.__edu_result.store_result(expected_outputs, TestCaseResult.PASS)
 else:
 self.__edu_result.store_result(expected_outputs, TestCaseResult.FAIL)

 return self.__edu_result

import { Traversal } from "./traversal.js";


export function mergeSorted(nums1, m, nums2, n){

   // Replace this placeholder return statement with your code

    return []
}

merge_sorted_array.yaml

testcases:
  - name: "testcase 1"
    inputs:
    - 1 : [1, 2, 3, 0, 0, 0]
    - 2 : 3
    - 3 : [4, 5, 6]
    - 4 : 3
    output: 
    - 1 : [1, 2, 3, 4, 5, 6]

  - name: "testcase 2"
    inputs:
    - 1 : [-1, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0]
    - 2 : 5
    - 3 : [-1, -1, 0, 0, 1, 2]
    - 4 : 6
    output: 
    - 1 : [-1, -1, -1, 0, 0, 0, 0, 0, 1, 2, 3]

  - name: "testcase 3"
    inputs:
    - 1 : [6, 7, 8, 9, 10, 0, 0, 0, 0, 0]
    - 2 : 5
    - 3 : [1, 2, 3, 4, 5]
    - 4 : 5
    output: 
    - 1 : [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

  - name: "testcase 4"
    inputs:
    - 1 : [10, 49, 99, 110, 176, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
    - 2 : 5
    - 3 : [1, 2, 4, 7, 8, 12, 15, 19, 24, 50, 69, 80, 100]
    - 4 : 13
    output: 
    - 1 : [1, 2, 4, 7, 8, 10, 12, 15, 19, 24, 49, 50, 69, 80, 99, 100, 110, 176]

  - name: "testcase 5"
    inputs:
    - 1 : [0, 1, 4, 9, 0, 0, 0, 0, 0, 0]
    - 2 : 4
    - 3 : [-111, -20, -5, 5, 11, 20]
    - 4 : 6
    output: 
    - 1 : [-111, -20, -5, 0, 1, 4, 5, 9, 11, 20]

def sum(input_1, input_2):
    return input_1+input_2

def validate_inputs(self) -> None:
 """
 self.__inputs is the list of inputs that are passed as input to function
 store the result using the self.store_result(error_msg, status)
 return : void
 """
 def is_sorted_arr2(arr):
 for i in range(len(arr) - 1):
 if arr[i] > arr[i + 1]:
 return False
 return True
 
 def check_decreasing_order(arr):
 if len(arr) == 1:
 return True
 count_zeros = 0
 start_index = None

 # Iterate from the end of the array
 for i in range(len(arr) - 1, -1, -1):
 if arr[i] == 0:
 count_zeros += 1
 else:
 start_index = i
 break

 if start_index is not None:
 if not(sorted(arr[:start_index+1])==(arr[:start_index+1])):
 return False

 return True

 def check_zeroes(arr):
 for i in arr:
 if(i!=0):
 return False
 return True
 
 def count_trailing_zeros(arr):
 count = 0
 for i in range(len(arr) - 1, -1, -1):
 if arr[i] == 0:
 count += 1
 else:
 break
 return count
 
 def is_valid_1d_array(arr):
 if not isinstance(arr, list):
 return False # Not a valid 1D array if it's not a list
 
 return all(isinstance(elem, int) and not isinstance(elem, bool) for elem in arr)

 # inputs can be accessed using self.__inputs starting from 0 to len(self.__inputs) - 1
 arr1 = self.__inputs[0]
 m = self.__inputs[1]
 arr2 = self.__inputs[2]
 n = self.__inputs[3]

 if not is_valid_1d_array(arr1):
 self.store_result(("Not a valid 1D Integer 'nums1' array."), ValidationFunction.FAIL)
 elif not is_valid_1d_array(arr2):
 self.store_result(("Not a valid 1D Integer 'nums2' array."), ValidationFunction.FAIL)
 elif not (0 <= len(arr1) <= 200):
 self.store_result ("'nums1' to have 0 <= size <= 200", ValidationFunction.FAIL)
 elif not (0 <= len(arr2) <= 200):
 self.store_result (("'nums2' to have 0 <= size <= 200" + str(arr2)), ValidationFunction.FAIL)
 elif not all(-1000 <= num <= 1000 for num in arr1):
 self.store_result ("'nums1' must consist of values from -1000 to 1000 only", ValidationFunction.FAIL)
 elif not all(-1000 <= num <= 1000 for num in arr2):
 self.store_result ("'nums2' must consist of values from -1000 to 1000 only", ValidationFunction.FAIL)
 elif not (0 <= m <= 200):
 self.store_result ("'m' should be from 0 to 200", ValidationFunction.FAIL)
 elif not (n <= 200):
 self.store_result ("'n' should be from 0 to 200", ValidationFunction.FAIL)
 elif not (len(arr2) == n):
 self.store_result ("'nums2' should have length equal to n", ValidationFunction.FAIL)
 elif not (1 <= m + n <= 200):
 self.store_result ("'m + n' should be from 1 to 200", ValidationFunction.FAIL)
 elif not len(arr1) == m + n or not count_trailing_zeros(arr1) == n:
 self.store_result ("'nums1' should have length equal to (m + n), where 'nums1' should have 'n' extra 0s at the end", ValidationFunction.FAIL)
 elif not is_sorted_arr2(arr2):
 self.store_result ("'nums2' should be sorted", ValidationFunction.FAIL)
 elif not check_decreasing_order(arr1):
 self.store_result(("'nums1' should be sorted " + str(arr1)), ValidationFunction.FAIL)
 else:
 self.store_result("", ValidationFunction.PASS)

Try to solve the Merge Sorted Array problem.

Merge Intervals

K-way Merge

Conclusion

Merge Sorted Array

Statement

Examples

Understand the problem

Figure it out!

Try it yourself