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Commit 3dc6df7

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Gonzalo Diaz
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[Hacker Rank] Interview Preparation Kit: Miscellaneous: Time Complexity: Primality. Solved ✓.
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# [Time Complexity: Primality](https://www.hackerrank.com/challenges/ctci-big-o)
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- Difficulty: `#medium`
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- Category: `#ProblemSolvingBasic`
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## Using bitwise operations
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A prime is a natural number greater than `1` that has no positive divisors other
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than `1` and itself.
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Given `p` integers, determine the primality of each integer and return `Prime`
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or `Not prime` on a new line.
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**Note**: If possible, try to come up with an $ \mathcal{O}(\sqrt{n}) $
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primality algorithm, or see what sort of optimizations you can come up with for
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san $ \mathcal{O}(\sqrt{n}) $ algorithm. Be sure to check out the Editorial
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after submitting your code.
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## Function Description
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Complete the primality function in the editor below.
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primality has the following parameter(s):
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- `int` n: an integer to test for primality
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## Returns
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- string: Prime if is prime, or Not prime
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## Input Format
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The first line contains an integer, , the number of integers to check for primality.
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Each of the subsequent lines contains an integer, , the number to test.
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## Constraints
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- $ 1 \leq p \leq 30 $
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- $ 1 \leq n \leq 2 ×ばつ 10^9 $
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## Sample Input
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```text
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STDIN Function
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----- --------
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3 p = 3 (number of values to follow)
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12 n = 12 (first number to check)
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5 n = 5
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7 n = 7
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```
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## Sample Output
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```text
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Not prime
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Prime
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Prime
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```
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## Explanation
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We check the following $ p = 3 $ integers for primality:
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1. $ n = 12 $ is divisible by numbers other than $ 1 $ and itself
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(i.e.: $ 2 ,ドル $ 3 ,ドル $ 4 ,ドル $ 6 $).
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1. $ n = 5 $ is only divisible and itself.
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1. $ n = 7 $ is only divisible and itself.
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// @link Problem definition [[docs/hackerrank/interview_preparation_kit/miscellaneous/ctci-big-o.md]]
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namespace algorithm_exercises_csharp.hackerrank.interview_preparation_kit.miscellaneous;
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using System.Diagnostics.CodeAnalysis;
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using System.Text;
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public static class TimeComplexityPrimality
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{
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private const string PRIME = "Prime";
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private const string NOT_PRIME = "Not prime";
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private static Int32? primeFactor(int n)
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{
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if (n < 2)
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{
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return null;
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}
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int divisor = n;
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Int32? maxPrimeFactor = null;
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int i = 2;
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while (i <= Math.Sqrt(divisor))
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{
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if (divisor % i == 0)
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{
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divisor = divisor / i;
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maxPrimeFactor = i;
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}
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else
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{
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i += 1;
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}
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}
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if (maxPrimeFactor == null)
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{
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return n;
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}
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return maxPrimeFactor;
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}
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/**
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* primality.
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*/
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public static string primality(int n)
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{
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Int32? pf = primeFactor(n);
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return (pf == null || pf != n) ? NOT_PRIME : PRIME;
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}
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}
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[
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{
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"title": "Sample Test case 0",
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"tests": [
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{
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"input": 12,
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"answer": "Not prime"
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},
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{
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"input": 5,
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"answer": "Prime"
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},
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{
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"input": 7,
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"answer": "Prime"
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}
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]
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},
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{
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"title": "Sample Test case 1",
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"tests": [
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{
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"input": 31,
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"answer": "Prime"
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},
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{
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"input": 33,
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"answer": "Not prime"
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}
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]
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},
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{
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"title": "Sample Test case 2",
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"tests": [
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{
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"input": 2,
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"answer": "Prime"
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},
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{
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"input": 7,
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"answer": "Prime"
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},
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{
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"input": 1982,
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"answer": "Not prime"
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},
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{
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"input": 14582734,
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"answer": "Not prime"
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},
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{
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"input": 9891,
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"answer": "Not prime"
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}
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]
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},
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{
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"title": "Sample Test case 0",
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"tests": [
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{
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"input": 1,
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"answer": "Not prime"
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}
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]
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}
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]
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namespace algorithm_exercises_csharp_test.hackerrank.interview_preparation_kit.miscellaneous;
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using algorithm_exercises_csharp_test.common;
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using algorithm_exercises_csharp.hackerrank.interview_preparation_kit.miscellaneous;
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[TestClass]
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public class TimeComplexityPrimalityTest
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{
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public class TimeComplexityPrimalityTestCaseTest(int input, String answer)
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{
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public int Input { get; } = input;
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public String Answer { get; } = answer;
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}
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public class TimeComplexityPrimalityTestCase(string title, List<TimeComplexityPrimalityTestCaseTest> tests)
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{
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public string Title { get; } = title;
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public List<TimeComplexityPrimalityTestCaseTest> Tests { get; } = tests;
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}
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private List<TimeComplexityPrimalityTestCase> testCases { get; set; } = default!;
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[TestInitialize]
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public void testInitialize()
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{
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testCases = JsonLoader.resourceLoad<List<TimeComplexityPrimalityTestCase>>(
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"hackerrank/interview_preparation_kit/miscellaneous/ctci_big_o.testcases.json"
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) ?? [];
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}
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[TestMethod]
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public void testTimeComplexityPrimality()
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{
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foreach (TimeComplexityPrimalityTestCase tests in testCases)
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{
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foreach (TimeComplexityPrimalityTestCaseTest test in tests.Tests)
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{
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String result = TimeComplexityPrimality.primality(test.Input);
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Assert.AreEqual(
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test.Answer,
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result,
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string.Format(
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System.Globalization.CultureInfo.InvariantCulture,
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"TimeComplexityPrimality.primality({0}) => must be: {1}",
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test.Input,
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test.Answer
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)
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);
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}
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}
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}
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}

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