London | May-2025 | Reza Jahanimir | sprint1

Sprint-1/fix/median.js

@@ -6,9 +6,40 @@
 // 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;
+
+  // Validate input — must be an array
+  if (!Array.isArray(list)) {
+    return null;
+  }
+
+  // Check if the input is an array and contains numeric values
+  const sortedList = list.filter(item => typeof item === 'number').sort((a, b) => a - b)
+
+  // find the middle index
+  const middleIndex = Math.floor(sortedList.length / 2);
+
+
+  // If the sorted list is empty, return null
+  if (sortedList.length === 0) {
+    return null; // Return null if there are no numeric values
+  } 
+
+  // If the length of the sorted list is even, add 0.5 to the middle number
+  if (sortedList.length % 2 === 0) {
+
+    // this is my wrong attempt for solving this logic but it will cause error
+    // return (sortedList[middleIndex - 1] + 0.5);
+
+    // tis is the correct way of finding the median when the length is even
+    return (sortedList[middleIndex - 1] + sortedList[middleIndex]) / 2;
+  }else {
+    // If the length of the sorted list is odd, return the middle number
+    return sortedList[middleIndex];
+  }
+
+
+  // const median = list.splice(middleIndex, 1)[0];
+  // return median;
 }
 
 module.exports = calculateMedian;

Sprint-1/fix/median.test.js

@@ -45,4 +45,9 @@ describe("calculateMedian", () => {
   ].forEach(({ input, expected }) =>
     it(`filters out non-numeric values and calculates the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
   );
+});
+
+// Failing Test Case for finding the middle number
+TestCase("If the length of the sorted list is even, add 0.5 to the middle number", () => {
+  expect(calculateMedian([4, 10])).toBe(7);
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,22 @@
-function dedupe() {}
+function dedupe(array) {
+  // Validate input
+  if (!Array.isArray(array)) return [];
+
+  // set is a collection of unique values
+  // It will automatically handle duplicates for us
+  const seen = new Set(); // {}
+  const result = [];
+
+  // Iterate through the array
+  // If the item is not in the set, add it to both the set and the result array
+  for (const item of array) {
+    if (!seen.has(item)) {
+      seen.add(item);
+      result.push(item);
+    }
+  }
+
+  return result;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,12 +16,25 @@ E.g. dedupe([1, 2, 1]) target output: [1, 2]
 // 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");
+test("Given an empty array, it should return an empty array", () => {
+    expect(dedupe([])).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("Given an array with no duplicates, it should return a copy of the original array", () => {
+    const input = [1, 2, 3];
+    expect(dedupe(input)).toEqual(input);
+});
 
 // Given an array with strings or numbers
 // When passed to the dedupe function
 // Then it should remove the duplicate values, preserving the first occurence of each element
+test ("Given an array with strings or numbers, it should remove the duplicate values, preserving the first occurrence of each element", () => {
+    expect(dedupe(['a', 'a', 'a', 'b', 'b', 'c'])).toEqual(['a', 'b', 'c']);
+    expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+    expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+});
+
+

Sprint-1/implement/max.js

@@ -1,4 +1,18 @@
 function findMax(elements) {
+  // Return -Infinity if the input is not an array
+  if (!Array.isArray(elements)) {
+    return -Infinity;
+  }
+
+  // Check if the input is an array and contains numeric values
+  const numericValues = elements
+    .filter((elements) => typeof elements === "number")
+
+  // If the sorted list is empty, return null
+  if (numericValues.length === 0) return -Infinity;
+
+  // Return the largest numeric value found in the array
+  return Math.max(...numericValues);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,48 @@ const findMax = require("./max.js");
 // 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");
+test("Given an empty array, it should return -Infinity", () => {
+    expect(findMax([])).toBe(-Infinity);
+}); 
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("Given an array with one number, it should return that number", () => {
+    expect(findMax([42])).toBe(42);
+}); 
 
 // 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 an array with both positive and negative numbers, it should return the largest number overall", () => {
+    expect(findMax([-10, 20, -30, 40])).toBe(40);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("Given an array with just negative numbers, it should return the closest one to zero", () => {
+    expect(findMax([-5, -10, -3])).toBe(-3);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+test("Given an array with decimal numbers, it should return the largest decimal number", () => {
+    expect(findMax([1.5, 2.3, 0.7])).toBe(2.3);
+});
 
 // 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 an array with non-number values, it should return the max and ignore non-numeric values", () => {
+    expect(findMax(['hey', 10, 'hi', 60, 10])).toBe(60);
+});
 
 // 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 an array with only non-number values, it should return -Infinity", () => {
+    expect(findMax(['a', 'b', 'c'])).toBe(-Infinity);
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,23 @@
 function sum(elements) {
+  // Return -Infinity if the input is not an array
+  if (!Array.isArray(elements)) {
+    return null;
+  }
+
+  // Check if the input is an array and contains numeric values
+  const numericValues = elements.filter(
+    (elements) => typeof elements === "number"
+  );
+
+  // If there are no numeric values, return 0
+  if (numericValues.length === 0) return 0;
+
+  // Return the sum of all numeric values in the array
+  let sum = 0;
+  for (let i = 0; i < numericValues.length; i++) {
+    sum += numericValues[i];
+  }
+    return sum;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,41 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+test("sum([]) returns 0", () => {
+  expect(sum([])).toBe(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+test("sum([5]) returns 5", () => {
+  expect(sum([5])).toBe(5);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("sum([-5, -10, -15]) returns -30", () => {
+  expect(sum([-5, -10, -15])).toBe(-30);
+}); 
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("sum([1.5, 2.5, 3.5]) returns 7.5", () => {
+  expect(sum([1.5, 2.5, 3.5])).toBe(7.5);
+});
 
 // 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("sum(['a', 10, 'b', 20]) returns 30", () => {
+  expect(sum(["a", 10, "b", 20])).toBe(30);
+}); 
 
 // 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("sum(['a', 'b', 'c']) returns 0", () => {
+  expect(sum(["a", "b", "c"])).toBe(0);
+});