Sum of all integers up to N

README.md

Summing up all numbers up to n

This is a comparison of two functions that sum up all the integer numbers from 1 to n and returns that sum.

Benchmarks

$ deno test --allow-read add.ts
Check file:///home/wperron/github.com/wperron/gists/add/add.ts
running 4 benchmarks ...
benchmark add ... 
    1001 runs avg: 31.842157842157842ms
benchmark recursive ... 
    1002 runs avg: 306.2614770459082ms
benchmark reduce ... 
    1003 runs avg: 309.7308075772682ms
benchmark wasm ... 
    1004 runs avg: 0.49203187250996017ms

add.ts

import { assertEquals } from "https://deno.land/std@0.98.0/testing/asserts.ts";
import { bench, runBenchmarks } from "https://deno.land/std@0.98.0/testing/bench.ts";
import { add as wasm } from "./pkg/add.js";

function add(n: number): number {
  if (n <= 0) return 0;
  let sum = 0;
  for (let i = 1; i <= n; i++) {
    sum += i;
  }
  return sum;
}

function recursive(n: number): number {
  if (n <= 0) {
    return 0;
  } else {
    return n + recursive(n - 1);
  }
}

function reduce(n: number): number {
  if (n <= 0) return 0;
  return new Array(n).fill(0).map((_, i) => i + 1).reduce((a, c) => a + c);
}

Deno.test({
  name: "add",
  fn() {
    assertEquals(6, add(3));
    assertEquals(10, add(4));
    assertEquals(1, add(1));
    assertEquals(0, add(0));
    assertEquals(0, add(-10));
  },
});

Deno.test({
  name: "recursive",
  fn() {
    assertEquals(6, recursive(3));
    assertEquals(10, recursive(4));
    assertEquals(1, recursive(1));
    assertEquals(0, recursive(0));
    assertEquals(0, recursive(-10));
  }
});

Deno.test({
  name: "reduce",
  fn() {
    assertEquals(6, reduce(3));
    assertEquals(10, reduce(4));
    assertEquals(1, reduce(1));
    assertEquals(0, reduce(0));
    assertEquals(0, reduce(-10));
  },
});

Deno.test({
  name: "wasm",
  fn() {
    assertEquals(6, wasm(3));
    assertEquals(10, wasm(4));
    assertEquals(1, wasm(1));
    assertEquals(0, wasm(0));
    assertEquals(0, wasm(-10));
  },
});

bench({
  name: "add",
  runs: 1001,
  func(b) {
    b.start();
    for (let i = 0; i < 1e5; i++) {
      add(1000);
    }
    b.stop();
  },
});

bench({
  name: "recursive",
  runs: 1002,
  func(b) {
    b.start();
    for (let i = 0; i < 1e5; i++) {
      recursive(1000);
    }
    b.stop();
  }
});

bench({
  name: "reduce",
  runs: 1003,
  func(b) {
    b.start();
    for (let i = 0; i < 1e5; i++) {
      reduce(1000);
    }
    b.stop();
  },
});

bench({
  name: "wasm",
  runs: 1004,
  func(b) {
    b.start();
    for (let i = 0; i < 1e5; i++) {
      wasm(1000);
    }
    b.stop();
  },
});

runBenchmarks();

lib.rs

use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub fn add(n: i32) -> i32 {
  if n <= 0 {
    return 0;
  }
  let mut sum = 0;
  for i in 1..n + 1 {
    sum += i;
  }
  return sum;
}