London | 26-ITP-May | Dipa Sarker | Sprint 1| Sprint-1-exercises

Sprint-1/fix/median.js

@@ -6,9 +6,28 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  const allNumbers = list.filter((item) => typeof item === "number");
+  if (allNumbers.length === 0) {
+    return null;
+  }
+
+  function compareNumbers(a, b) {
+    return a - b;
+  }
+  const sortedNumbers = allNumbers.sort(compareNumbers);
+  let result = 0;
+  for (i = 0; i < sortedNumbers.length; i++) result += sortedNumbers[i];
+  if (sortedNumbers.length % 2 === 0) {
+    const median = result / sortedNumbers.length;
+    return median;
+  }
+  if (sortedNumbers.length % 2 !== 0) {
+    const middleIndex = Math.floor(sortedNumbers.length / 2);
+    return sortedNumbers[middleIndex];
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,10 @@
-function dedupe() {}
+function dedupe(array) {
+  if (array.length === 0) {
+    return [];
+  }
+  const set = new Set(array);
+  const newArray = Array.from(set);
+  return newArray;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,28 +1,40 @@
 const dedupe = require("./dedupe.js");
-/*
-Dedupe Array
 
-📖 Dedupe means **deduplicate**
+describe("dedupe", () => {
+  test("given an empty array, it should return an empty array", () => {
+    expect(dedupe([])).toEqual([]);
+  });
+  test.each([
+    {
+      input: [1, 2, 3, 4],
+      expected: [1, 2, 3, 4],
+    },
+    {
+      input: ["a", "b", "c"],
+      expected: ["a", "b", "c"],
+    },
+  ])("returns a copy of an array with no duplicates", ({ input, expected }) => {
+    const result = dedupe(input);
 
-In this kata, you will need to deduplicate the elements of an array
+    expect(result).toEqual(expected);
+    expect(result).not.toBe(input);
+  });
+  test.each([
+    {
+      input: ["a", "c", "b", "d", "c", "d"],
+      expected: ["a", "c", "b", "d"],
+    },
+    {
+      input: [1, 2, 3, 2, 4, 3],
+      expected: [1, 2, 3, 4],
+    },
+  ])(
+    "given an array with duplicates, it should remove duplicates and preserve first occurrence",
+    ({ input, expected }) => {
+      const result = dedupe(input);
 
-E.g. dedupe(['a','a','a','b','b','c']) returns ['a','b','c']
-E.g. dedupe([5, 1, 1, 2, 3, 2, 5, 8]) returns [5, 1, 2, 3, 8]
-E.g. dedupe([1, 2, 1]) returns [1, 2]
-*/
-
-// Acceptance Criteria:
-
-// Given an empty array
-// When passed to the dedupe function
-// Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
-
-// Given an array with no duplicates
-// When passed to the dedupe function
-// Then it should return a copy of the original array
-
-// Given an array of strings or numbers
-// When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
-// first occurrence of each element from the original array.
+      expect(result).toEqual(expected);
+      expect(result).not.toBe(input);
+    }
+  );
+});

Sprint-1/implement/max.js

@@ -1,4 +1,12 @@
-function findMax(elements) {
+function findMax(array) {
+  let result = -Infinity;
+
+  for (const element of array) {
+    if (typeof element === "number" && element > result) {
+      result = element;
+    }
+  }
+  return result;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -1,43 +1,31 @@
-/* Find the maximum element of an array of numbers
-
-In this kata, you will need to implement a function that find the largest numerical element of an array.
-
-E.g. max([30, 50, 10, 40]), target output: 50
-E.g. max(['hey', 10, 'hi', 60, 10]), target output: 60 (sum ignores any non-numerical elements)
-
-You should implement this function in max.js, and add tests for it in this file.
-
-We have set things up already so that this file can see your function from the other file.
-*/
-
 const findMax = require("./max.js");
 
-// Given an empty array
-// When passed to the max function
-// Then it should return -Infinity
-// Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+describe("findMax", () => {
+  test("given an empty array, it should return -Infinity", () => {
+    expect(findMax([])).toEqual(-Infinity);
+  });
 
-// Given an array with one number
-// When passed to the max function
-// Then it should return that number
+  test("given array with one number, it should return that number", () => {
+    expect(findMax([5])).toEqual(5);
+  });
 
-// Given an array with both positive and negative numbers
-// When passed to the max function
-// Then it should return the largest number overall
+  test("given array with both +ve and -ve numbers, it should return the largest number overall", () => {
+    expect(findMax([-10, 5, -20, 3])).toEqual(5);
+  });
 
-// Given an array with just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
+  test("given array with only -ve numbers, it should return the closest one to zero", () => {
+    expect(findMax([-10, -20, -30, -40])).toEqual(-10);
+  });
 
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
+  test("given array with decimal numbers, it should return the largest decimal number", () => {
+    expect(findMax([0.5, 0.12, 5.6, 0.002])).toEqual(5.6);
+  });
 
-// Given an array with non-number values
-// When passed to the max function
-// Then it should return the max and ignore non-numeric values
+  test("given array with non-number values, it should return the max and ignore non-numeric values", () => {
+    expect(findMax([5, "a", 10, "cat", 3, "b"])).toEqual(10);
+  });
 
-// Given an array with only non-number values
-// When passed to the max function
-// Then it should return the least surprising value given how it behaves for all other inputs
+  test("given array with only non-number values, it should return -infinity", () => {
+    expect(findMax(["cow", "cat", "dog"])).toEqual(-Infinity);
+  });
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,11 @@
-function sum(elements) {
+function sum(array) {
+  let result = 0;
+  for (const element of array) {
+    if (typeof element === "number") {
+      result += element;
+    }
+  }
+  return result;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -1,36 +1,27 @@
-/* Sum the numbers in an array
-
-In this kata, you will need to implement a function that sums the numerical elements of an array
-
-E.g. sum([10, 20, 30]), target output: 60
-E.g. sum(['hey', 10, 'hi', 60, 10]), target output: 80 (ignore any non-numerical elements)
-*/
-
 const sum = require("./sum.js");
 
-// Acceptance Criteria:
-
-// Given an empty array
-// When passed to the sum function
-// Then it should return 0
-test.todo("given an empty array, returns 0")
+describe("sum", () => {
+  test("given an empty array, it should return 0", () => {
+    expect(sum([])).toEqual(0);
+  });
 
-// Given an array with just one number
-// When passed to the sum function
-// Then it should return that number
+  test("given array with one number, it should return that number", () => {
+    expect(sum([5])).toEqual(5);
+  });
 
-// Given an array containing negative numbers
-// When passed to the sum function
-// Then it should still return the correct total sum
+  test("given array with only -ve numbers, it should return the correct total sum", () => {
+    expect(sum([-10, -20, -30, -40])).toEqual(-100);
+  });
 
-// Given an array with decimal/float numbers
-// When passed to the sum function
-// Then it should return the correct total sum
+  test("given array with only decimal/float numbers, it should return the correct total sum", () => {
+    expect(sum([0.5, 0.12, 3.14, 0.002])).toEqual(3.762);
+  });
 
-// Given an array containing non-number values
-// When passed to the sum function
-// Then it should ignore the non-numerical values and return the sum of the numerical elements
+  test("given array with non-number values, it should return the sum of the numerical elements", () => {
+    expect(sum([1, "a", 0.5, "b", -10])).toEqual(-8.5);
+  });
 
-// Given an array with only non-number values
-// When passed to the sum function
-// Then it should return the least surprising value given how it behaves for all other inputs
+  test("given array with only non-number values, it should return 0", () => {
+    expect(sum(["cow", "cat", "dog"])).toEqual(0);
+  });
+});

Sprint-1/refactor/includes.js

@@ -1,8 +1,5 @@
-// Refactor the implementation of includes to use a for...of loop
-
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
+  for (const element of list) {
     if (element === target) {
       return true;
     }

Sprint-1/stretch/aoc-2018-day1/solution.js

@@ -0,0 +1,16 @@
+const fs = require("fs");
+
+const text = fs.readFileSync("./input.txt", "utf8");
+
+const numbers = text
+  .trim()
+  .split("\n")
+  .map(Number);
+
+let frequency = 0;
+
+for (const number of numbers) {
+  frequency += number;
+}
+
+console.log(frequency);