(euler) - #10 and export {}

euler/gulpfile.js

@@ -13,7 +13,7 @@ gulp.task('build', () => {
         .pipe(
             rename(path => {
                 if (path.basename === 'utils') return;
-                path.basename = path.basename.substr(0, 1);
+                path.basename = path.basename.split('-')[0].trim();
             })
         )
         .pipe(gulp.dest('build'));

euler/src/1 - Multiples of 3 or 5.ts

@@ -1,4 +1,6 @@
-import { calcSum } from './utils';
+export {};
+
+const calcSum = (numbers: number[]) => numbers.reduce((a, b) => a + b);
 
 const multiplesOf = (numbers: number[], upperBound: number) => {
     const results: Set<number> = new Set();

euler/src/10 - Sumation of Primes.ts

@@ -0,0 +1,35 @@
+export {};
+
+const calcSum = (numbers: number[]) => numbers.reduce((a, b) => a + b);
+
+// Sieve of Eratosthenes time!!!
+const sumOfPrimes = (upperBound: number) => {
+    let array: boolean[] = [];
+    let upperLimit = Math.sqrt(upperBound);
+    let output: number[] = [];
+
+    // Make an array from 2 to (n - 1) of truthy values
+    for (var i = 0; i < upperBound; i++) {
+        array.push(true);
+    }
+
+    // Remove multiples of primes starting from 2, 3, 5,...
+    for (var i = 2; i <= upperLimit; i++) {
+        if (array[i]) {
+            for (var j = i * i; j < upperBound; j += i) {
+                array[j] = false;
+            }
+        }
+    }
+
+    // All array[i] set to true are primes
+    for (var i = 2; i < upperBound; i++) {
+        if (array[i]) {
+            output.push(i);
+        }
+    }
+
+    return calcSum(output);
+};
+
+console.log(sumOfPrimes(2000000));

euler/src/2 - Even Fibonacci Numbers.ts

@@ -1,4 +1,6 @@
-import { calcSum } from './utils';
+export {};
+
+const calcSum = (numbers: number[]) => numbers.reduce((a, b) => a + b);
 
 const fibonacciNumbers = (upperBound: number) => {
     const sequence = [1, 2];

euler/src/3 - Largest Prime Factor.ts

@@ -1,3 +1,5 @@
+export {};
+
 const largestPrimeFactor = (number: number) => {
     let i = 2;
 

euler/src/4 - Largest Palindrome Number.ts

@@ -1,3 +1,5 @@
+export {};
+
 const largestPallidromeNumber = (lowerBound: number, upperBound: number) => {
     // Work out all of the products of 3 digit numbers
     const products: number[] = [];

euler/src/5 - Smallest Number.ts

@@ -1,3 +1,5 @@
+export {};
+
 /**
  * Is x disible to n?
  */

euler/src/6 - Sum Square Difference.ts

@@ -1,4 +1,6 @@
-import { calcSum } from './utils';
+export {};
+
+const calcSum = (numbers: number[]) => numbers.reduce((a, b) => a + b);
 
 const sumOfSquares = (lowerBound: number, upperBound: number) => {
     // Calculate the square number of all the numbers between the bounds

euler/src/7 - 10001st Prime.ts

@@ -1,3 +1,5 @@
+export {};
+
 const isPrime = (number: number) => {
     for (var i = 2; i < number; i++) {
         if (number % i === 0) return false;

euler/src/8 - Largest Product in a Series.ts

@@ -1,3 +1,5 @@
+export {};
+
 const largestProduct = (number: bigint | number, adjacentDigits: number) => {
     let cursorIndex = 0;
     const selections: number[][] = [];

euler/src/9 - Special Pythagorean Triplet.ts

@@ -1,3 +1,5 @@
+export {};
+
 // a + b + c = 1000
 // we need a * b * c
 // pythagorean triplet: a < b < c

euler/src/utils.ts

@@ -1,4 +0,0 @@
-/**
- * Calculates the sum of an array of numbers.
- */
-export const calcSum = (numbers: number[]) => numbers.reduce((a, b) => a + b);