exercise-typescript-arrays.md

Practice: TypeScript arrays

Intro

• For this exercise, you can work on your local environment (if you have the TypeScript compiler installed).

• Or, if you prefer, you can work on an online editor like Stackblitz. For example, you can write your TypeScript code here:
  

https://stackblitz.com/edit/typescript-vkcluy?file=index.ts

Iteration 1 - Create a function countOddStrings()

Requirements:

• Name of the function: countOddStrings
• Parameters:
  • stringList (an array of strings) - required.
• Return value:
  • Return the amount of elements in the array that have an odd number of characters.
• Notes:
  • You can assume all strings in the array are non-empty.

Iteration 2 - Create a function getUniqueNumbers()

Requirements:

• Name of the function: getUniqueNumbers
• Parameters:
  • numbersArr (an array of numbers) - required.
• Return value:
  • Return a new array that contains only unique numbers from the input array, in the same order they first appeared.
• Notes:
  • You may assume the input array contains only numbers.
  • The order of numbers should be preserved, and duplicates should be removed.
  • Your function should return a new array (ie. it should not modify the original array)

Examples:

const test1 = getUniqueNumbers([]);
console.log(test1); // expected: []

const test2 = getUniqueNumbers([1, 2, 3]);
console.log(test2); // expected: [1, 2, 3]

const test3 = getUniqueNumbers([10, 5, 20, 5, 30, 5]);
console.log(test3); // expected: [10, 5, 20, 30]

const test4 = getUniqueNumbers([100, 3, -20, 3, -20, 100, 500]);
console.log(test4); // expected: [100, 3, -20, 500]

Bonus - Create a function findMaxInMatrix()

Requirements:

• Name of the function: findMaxInMatrix
• Parameters:
  • matrix (a 2D array of numbers) - required.
• Return value:
  • A single number representing the maximum value in the entire 2D array.
• Notes:
  • If the matrix is empty, return null.
  • The function should not modify the original matrix.

Examples:

const matrixA = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9],
];

const matrixB = [
  [],
  [],
];

findMaxInMatrix(matrixA); // expected: 9
findMaxInMatrix(matrixB); // expected: null

Solutions

• Iteration 1: https://stackblitz.com/edit/typescript-exvzaa?file=index.ts
• Iteration 2 - Option 1 (with a forEach): https://stackblitz.com/edit/typescript-71iiw8?file=index.ts
• Iteration 2 - Option 2 (with a Set): https://stackblitz.com/edit/typescript-quuthp?file=index.ts