[JS][7kyu] Pernicious Numbers

codewars/7kyu/pernicious-numbers/koronya.js

@@ -0,0 +1,67 @@
+// [JS][7kyu] Pernicious Numbers
+// pernicious-numbers
+// https://www.codewars.com/kata/56e195d02bb22479e50016af/train/javascript
+
+const getDigitSum = (num) =>
+  num
+    .toString(2)
+    .split('')
+    .reduce((acc, curr) => acc + Number(curr), 0)
+
+getDigitSum(25)
+getDigitSum(75)
+
+const primeMap = new Map()
+primeMap.set(2, true)
+
+const isPrimeNumber = (num) => {
+  if (primeMap.has(num)) {
+    return primeMap.get(num)
+  }
+
+  const rangeNum = Math.floor(Math.sqrt(num))
+  if (num % 2 === 0 || num === 1) {
+    primeMap.set(num, false)
+    return false
+  }
+  for (let i = 3; i <= rangeNum; i += 2) {
+    if (num % i === 0) {
+      primeMap.set(num, false)
+      return false
+    }
+  }
+
+  primeMap.set(num, true)
+  return true
+}
+
+const pernicious = (n) => {
+  if (n < 0) {
+    return 'No pernicious numbers'
+  }
+  const limit = Math.floor(n)
+
+  const result = []
+  for (let i = 3; i <= limit; i += 1 || 0) {
+    if (isPrimeNumber(getDigitSum(i))) {
+      result.push(i)
+    }
+  }
+
+  if (result.length === 0) {
+    return 'No pernicious numbers'
+  }
+  return result
+}
+
+pernicious(4)
+pernicious(5)
+pernicious(232)
+
+pernicious(0)
+pernicious(1)
+pernicious(-54)
+
+pernicious(6.99)
+pernicious(-6.99)
+pernicious(42.42424242)