Learn and practice the Bitwise Manipulation, Sliding Window, and Union Find patterns to solve coding interview problems.

Educative-77 in C++: Accelerate Your Coding Interview Prep

Each of the patterns in this module exemplifies the power of dissecting a problem in detail and figuring out the least expensive operations required to solve it. In the Bitwise Manipulation pattern, we’ll learn to leverage the power of bit-level operators to deliver more efficient solutions. With the Sliding Window pattern, we’ll gain practice in various techniques to ensure that a solution that seems to require nested loops actually executes in linear time. Using the Union Find pattern, we’ll learn to solve a diverse set of problems using the disjoint-set data structure.

Elegant by Design

# Statement

For any $n$ positive number in base 10, return the complement of its binary representation as an integer in base 10.

**Constraints**

* $0 \leq n \leq 10^9$

# Examples

# Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

What is the correct output if the following value is given as input?

Input = 39


What is the correct output if the following value is given as input?
Input = 39

What is the correct output if the following value is given as input?

Input = 150


What is the correct output if the following value is given as input?
Input = 150

What is the correct output if the following value is given as input?

Input = 293


What is the correct output if the following value is given as input?
Input = 293

What is the binary complement of 100101101?

What is the binary complement of 100101101?

What is the binary complement of 1000110111?

What is the binary complement of 1000110111?

What is the resulting bits set after taking the $XOR$ of 10011011011 with 11111111111?

What is the resulting bits set after taking the <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>X</mi><mi>O</mi><mi>R</mi></mrow><annotation encoding="application/x-tex">XOR</annotation></semantics></math>XOR of 10011011011 with 11111111111?

Complement of Base 10 Number

Complement of Base 10 Number

# 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.

# 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: `FindBitwiseComplement`\n- Candidate's submitted solution code: USER_CODE\n- Error: ERROR_DESCRIPTION\n- Failed test case: FAILED_TEST_CASE\n- Coding language: `C++`\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 `FindBitwiseComplement` 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 `FindBitwiseComplement`.\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) `FindBitwiseComplement`. \n- While calculating time complexity, include the time complexity of built-in C++ 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) `FindBitwiseComplement`. \n- While calculating space complexity, include the space complexity of built-in C++ 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
        """

        from math import log2, floor


        def find_bitwise_complement(num):
            if num == 0:
                return 1

            bit_count = floor(log2(num)) + 1
            all_bits_set = pow(2, bit_count) - 1
            return num ^ all_bits_set


        expected = find_bitwise_complement(self.__inputs[0])

        actual = self.__actual_outputs[0]
        # multiple outputs will be added at each index respectively for a single test_case
        expected_outputs = [] 
        # store the 1st expected output that should be displayed to the user 
        expected_outputs.append(expected)
        if expected == actual:
            self.__edu_result.store_result(expected_outputs, TestCaseResult.PASS)
        else:
            self.__edu_result.store_result(expected_outputs, TestCaseResult.FAIL)

        return self.__edu_result

#include <iostream>
#include <cmath>
#include <vector>

int BitwiseComplement(int num){

 // Replace this placeholder return statement with your code
 return -1;
}

complement_of_base_10_number.yaml

testcases:
  - name: "testcase 1"
    inputs:
    - 1 : 42
    output: 
    - 1 : 21
  - name: "testcase 2"
    inputs:
    - 1: 8
    output:
    - 1 : 7
  - name: "testcase 3"
    inputs:
    - 1: 233
    output:
    - 1: 22
  - name: "testcase 4"
    inputs:
    - 1: 100
    output:
    - 1: 27
  - name: "testcase 5"
    inputs:
    - 1: 11111
    output:
    - 1: 5272

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
 """
 # inputs can be accessed using self.__inputs starting from 0 to len(self.__inputs) - 1
 n = self.__inputs[0]

 if not (0 <= n <= 10**9):
 self.store_result("Value of 'n' should be in the range 0 <= n <= 10^9", ValidationFunction.FAIL)
 else:
 self.store_result("", ValidationFunction.PASS)

Try to solve the Complement of Base 10 Integer problem.

Bitwise Manipulation

Sliding Window

Union Find

Conclusion

Complement of Base 10 Number

Statement

Examples

Understand the problem

Figure it out!

Try it yourself