Start a new Kumite
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Kumite (ko͞omiˌtā) is the practice of taking techniques learned from Kata and applying them through the act of freestyle sparring.

You can create a new kumite by providing some initial code and optionally some test cases. From there other warriors can spar with you, by enhancing, refactoring and translating your code. There is no limit to how many warriors you can spar with.

A great use for kumite is to begin an idea for a kata as one. You can collaborate with other code warriors until you have it right, then you can convert it to a kata.

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McCodevs.McCode

Fast Primality Test in Python

We can turn this into a one-liner (minus the import)

Code
Diff
  • from math import sqrt

is_prime = lambda n: n == 2 or (n > 2 and n % 2 != 0 and all(n % x != 0 for x in range(3, int(sqrt(n)) + 1, 2)))
    • from math import sqrt
    • is_prime = lambda n: n == 2 or (n > 2 and n % 2 != 0 and all(n % x != 0 for x in range(3, int(sqrt(n)) + 1, 2)))
    • def is_prime(n):
    • if n < 2:
    • return False
    • elif n == 2:
    • return True
    • elif n % 2 == 0:
    • return False
    • for x in range(3, int(sqrt(n)) + 1, 2):
    • if n % x == 0:
    • return False
    • return True
ofourniervs.user63037Failed Tests

Bubble sort implemented in GO

Code
Diff
  • package main

import "fmt"



func bubble_sort(dataset []int, amout_of_integers int){
  for i := 0; i <= amout_of_integers; i++ {
    for j := amout_of_integers; j >= i + 1; j-- {
      if dataset[j] < dataset[j-1] {
        dataset[j], dataset[j-1] = dataset[j-1], dataset[j] 
      }
    }
  }
}


func main(){

  dataset := []int{5, 2, 4, 6, 1, 3};

  fmt.Println(dataset)

  bubble_sort(dataset, 5);

  fmt.Println(dataset)
}
    • package main
    • import "fmt"
    • func swap(dataset []int, a, b int) {
    • var x int = dataset[a]
    • dataset[a] = dataset[b]
    • dataset[b] = x
    • }
    • func bubble_sort(dataset []int, amout_of_integers int){
    • for i := 0; i <= amout_of_integers; i++ {
    • for j := amout_of_integers; j >= i + 1; j-- {
    • if dataset[j] < dataset[j-1] {
    • swap(dataset, j, j - 1)
    • dataset[j], dataset[j-1] = dataset[j-1], dataset[j]
    • }
    • }
    • }
    • }
    • func main(){
    • dataset := []int{5, 2, 4, 6, 1, 3};
    • fmt.Println(dataset)
    • bubble_sort(dataset, 5);
    • fmt.Println(dataset)
    • }
ofourniervs.raulbc777

Distance Between Two Points in a Plane and in the Space.

Code
Diff
  • from math import sqrt

def distance2D(pA, pB):
    if pA == pB: return 0
    (xA, yA), (xB, yB) = pA, pB
    return sqrt((xA - xB)**2 + (yA - yB)**2)
    
def distance3D(pA, pB):
    if pA == pB: return 0
    (xA, yA, zA), (xB, yB, zB) = pA, pB
    return sqrt((xA - xB)**2 + (yA - yB)**2 + (zA - zB) **2)
    • from math import sqrt
    • def distance2D(pA, pB):
    • if pA == pB: return 0
    • xA, yA = tuple(pA); xB, yB = tuple(pB)
    • (xA, yA), (xB, yB) = pA, pB
    • return sqrt((xA - xB)**2 + (yA - yB)**2)
    • def distance3D(pA, pB):
    • if pA == pB: return 0
    • xA, yA, zA = tuple(pA); xB, yB, zB = tuple(pB)
    • (xA, yA, zA), (xB, yB, zB) = pA, pB
    • return sqrt((xA - xB)**2 + (yA - yB)**2 + (zA - zB) **2)
ofourniervs.Posydon

Last Char

Strings
Data Types
Code
Diff
  • from operator import itemgetter

last_char = itemgetter(-1)
    • last_char = lambda s: s[-1]
    • from operator import itemgetter
    • last_char = itemgetter(-1)
dinglemousevs.dinglemouse

Airport Arrivals/Departures Pretty Print

Code
Diff
  • public class Dinglemouse {

  // Use CSS to display a pretty version of the flap display
  // From: https://www.codewars.com/kata/airport-arrivals-slash-departures-number-1/java
  public static String[] prettyPrint(final String[] lines) {
    String s = "";
    for (int y = 0; y < lines.length; y++) {
      s += "<div style=\"height:23px\">";
      for (int x = 0; x < lines[y].length(); x++) {
        s += "<span style=\"font-size:10px;color:yellow;padding:5px;border:1px solid gray;background:black\">"+lines[y].charAt(x)+"</span>";
      }
      s += "</div>";
    }
    System.out.println(s);
    return lines;
  }

}
    • public class Dinglemouse {
    • // Use CSS to display a pretty version of the flap display
    • // From: https://www.codewars.com/kata/airport-arrivals-slash-departures-number-1/java
    • public static String[] prettyPrint(final String[] lines) {
    • String s = "<pre>";
    • String s = "";
    • for (int y = 0; y < lines.length; y++) {
    • s += "<div style=\"height:23px\">";
    • for (int x = 0; x < lines[y].length(); x++) {
    • s += "<span style=\"font-size:10px;color:yellow;padding:5px;border:1px solid gray;background:black\">"+lines[y].charAt(x)+"</span>";
    • }
    • s += "</div>";
    • }
    • s+= "</pre>";
    • System.out.println(s);
    • return lines;
    • }
    • }
knilnissimvs.donaldsebleung

Dice Generator

Mathematics
Algorithms
Logic
Numbers
Fundamentals
Code
Diff
  • const dice = _ => -~(Math.random()*6);
    • const dice=_=>~~(Math.random()*6)+1;
    • const dice = _ => -~(Math.random()*6);
knilnissimvs.mokahaiku

Middle Character

Code
Diff
  • const middleCharacter = s => s.slice(~(s.length/2), -~(s.length/2));
    • const middleCharacter = s => s.slice(s.length/2 - !(s.length % 2), s.length/2+1);
    • const middleCharacter = s => s.slice(~(s.length/2), -~(s.length/2));
dinglemousevs.alinodev

Palindrome Dates

Code
Diff
  • package com.mystuff.juststuff;

import java.text.*;
import java.util.*;

public class Palindrome {

	private static final SimpleDateFormat sdf = new SimpleDateFormat("MMddyyyy");

	public Set<Date> countDatePalindromes(final Date startDate, final Date endDate) {
		final Set<Date> set = new TreeSet<>();
		final GregorianCalendar startCal = new GregorianCalendar();
		final GregorianCalendar endCal = new GregorianCalendar();

    // If end date is before start date, flip them.
    startCal.setTime(startDate.before(endDate) ? startDate : endDate);
    endCal.setTime(startDate.after(endDate) ? startDate : endDate);
    
		for (; startCal.before(endCal) || startCal.equals(endCal); startCal.add(Calendar.DAY_OF_MONTH, 1)) {   
			final String forward = sdf.format(startCal.getTime());
      final String back = new StringBuilder(forward).reverse().toString();            
			if (forward.equals(back)) {
        set.add(startCal.getTime()); // Date string looks same both ways	
      }
		}	
    
		return set;
	}
	
}
    • package com.mystuff.juststuff;
    • import java.text.*;
    • import java.util.Calendar;
    • import java.util.Date;
    • import java.util.GregorianCalendar;
    • import java.util.TreeSet;
    • import java.util.*;
    • public class Palindrome {
    • SimpleDateFormat sdf;
    • public Palindrome() {
    • this.sdf = new SimpleDateFormat("MMddyyyy");
    • sdf.setLenient(false);
    • }
    • public TreeSet<Date> countDatePalindromes(Date startDate, Date endDate) {
    • TreeSet<Date> palSet = new TreeSet<Date>();
    • GregorianCalendar startCal = new GregorianCalendar();
    • GregorianCalendar endCal = new GregorianCalendar();
    • private static final SimpleDateFormat sdf = new SimpleDateFormat("MMddyyyy");
    • /*
    • end date is chronologically before start date. flip them.
    • NOTE: lines 23-30 should be a pre-condition to the countDatePalindromes method,
    • so they should be deleted.
    • */
    • if (startDate.getTime() > endDate.getTime()) {
    • startCal.setTime(endDate);
    • endCal.setTime(startDate);
    • }else {
    • startCal.setTime(startDate);
    • endCal.setTime(endDate);
    • }
    • String regularDate = null;
    • String palDate = null;
    • while ( (startCal.before(endCal)) || (startCal.equals(endCal)) ) {
    • regularDate = sdf.format(startCal.getTime());
    • palDate = palindromify(startCal.getTime());
    • // a date palindrome was found
    • if (regularDate.equals(palDate))
    • palSet.add(startCal.getTime());
    • startCal.add(Calendar.DAY_OF_MONTH, 1);
    • public Set<Date> countDatePalindromes(final Date startDate, final Date endDate) {
    • final Set<Date> set = new TreeSet<>();
    • final GregorianCalendar startCal = new GregorianCalendar();
    • final GregorianCalendar endCal = new GregorianCalendar();
    • // If end date is before start date, flip them.
    • startCal.setTime(startDate.before(endDate) ? startDate : endDate);
    • endCal.setTime(startDate.after(endDate) ? startDate : endDate);
    • for (; startCal.before(endCal) || startCal.equals(endCal); startCal.add(Calendar.DAY_OF_MONTH, 1)) {
    • final String forward = sdf.format(startCal.getTime());
    • final String back = new StringBuilder(forward).reverse().toString();
    • if (forward.equals(back)) {
    • set.add(startCal.getTime()); // Date string looks same both ways
    • }
    • }
    • return palSet;
    • return set;
    • }
    • private String palindromify(final Date arg) {
    • StringBuffer palBuff = new StringBuffer(8);
    • palBuff = sdf.format(arg, palBuff, new FieldPosition(0));
    • return palBuff.reverse().toString();
    • }
    • }
dinglemousevs.dinglemouse

Get Factors

Code
Diff
  • function getFactors (n) {
  if (!Number.isInteger(n) || n < 1) return [];
  
  var divisors = new Set(); 
  var step = n % 2 == 0 ? 1 : 2;
  for (let i = 1; i <= Math.sqrt(n); i += step) {
    if (n % i == 0) divisors.add(i).add(n/i)
  }
  return Array.from(divisors).sort((a,b)=>a-b)
}
    • function getFactors (n) {
    • if (!Number.isInteger(n) || n < 1) return [];
    • var divisors = new Set();
    • for (let i = 1; i <= Math.sqrt(n); i++) {
    • var divisors = new Set();
    • var step = n % 2 == 0 ? 1 : 2;
    • for (let i = 1; i <= Math.sqrt(n); i += step) {
    • if (n % i == 0) divisors.add(i).add(n/i)
    • }
    • return Array.from(divisors)
    • return Array.from(divisors).sort((a,b)=>a-b)
    • }